diff --git a/src/H5FDros3.c b/src/H5FDros3.c
index c8747754860..2208affa8fa 100644
--- a/src/H5FDros3.c
+++ b/src/H5FDros3.c
@@ -47,6 +47,10 @@
  */
 static hid_t H5FD_ROS3_g = 0;
 
+/* Session/security token property name
+ */
+#define ROS3_TOKEN_PROP_NAME "ros3_token_prop"
+
 #if ROS3_STATS
 
 /* arbitrarily large value, such that any reasonable size read will be "less"
@@ -566,6 +570,257 @@ H5FD__ros3_fapl_free(void *_fa)
     FUNC_LEAVE_NOAPI(SUCCEED)
 } /* end H5FD__ros3_fapl_free() */
 
+/*-------------------------------------------------------------------------
+ * Function:    H5Pget_fapl_ros3_token
+ *
+ * Purpose:     Returns session/security token of the ros3 file access
+ *              property list though the function arguments.
+ *
+ * Return:      Success:        Non-negative
+ *
+ *              Failure:        Negative
+ *
+ * Programmer:  Jan-Willem Blokland
+ *              2023-05-26
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pget_fapl_ros3_token(hid_t fapl_id, size_t size, char *token_dst /*out*/)
+{
+    H5P_genplist_t *plist = NULL;
+    char           *token_src;
+    htri_t          token_exists;
+    size_t          tokenlen  = 0;
+    herr_t          ret_value = SUCCEED;
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE3("e", "izx", fapl_id, size, token_dst);
+
+#if ROS3_DEBUG
+    fprintf(stdout, "H5Pget_fapl_ros3_token() called.\n");
+#endif
+
+    if (size == 0)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "size cannot be zero.")
+    if (token_dst == NULL)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "token_dst is NULL")
+
+    if (NULL == (plist = H5P_object_verify(fapl_id, H5P_FILE_ACCESS)))
+        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a file access property list")
+    if (H5FD_ROS3 != H5P_peek_driver(plist))
+        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "incorrect VFL driver")
+    if ((token_exists = H5P_exist_plist(plist, ROS3_TOKEN_PROP_NAME)) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "failed to check if property token exists in plist")
+    if (token_exists) {
+        if (H5P_get(plist, ROS3_TOKEN_PROP_NAME, &token_src) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get token value")
+    }
+
+    /* Copy the token data out */
+    tokenlen = HDstrlen(token_src);
+    if (size <= tokenlen) {
+        tokenlen = size - 1;
+    }
+    H5MM_memcpy(token_dst, token_src, sizeof(char) * tokenlen);
+    token_dst[tokenlen] = '\0';
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pget_fapl_ros3_token() */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD__ros3_str_token_copy()
+ *
+ * Purpose:     Create a copy of the token string.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ * Programmer:  Jan-Willem Blokland
+ *              2023-05-26
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5FD__ros3_str_token_copy(const char H5_ATTR_UNUSED *name, size_t H5_ATTR_UNUSED size, void *_value)
+{
+    char **value     = (char **)_value;
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_PACKAGE
+
+#if ROS3_DEBUG
+    fprintf(stdout, "H5FD__ros3_str_token_copy() called.\n");
+#endif
+
+    if (*value)
+        if (NULL == (*value = HDstrdup(*value)))
+            HGOTO_ERROR(H5E_RESOURCE, H5E_CANTALLOC, FAIL, "can't copy string property token")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5FD__ros3_str_token_copy() */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD__ros3_str_token_cmp()
+ *
+ * Purpose:     Compares two token strings with each other.
+ *
+ * Return:
+ *     - Equivalent:     0
+ *     - Not Equivalent: non-zero value
+ *
+ * Programmer:  Jan-Willem Blokland
+ *              2023-05-26
+ *
+ *-------------------------------------------------------------------------
+ */
+static int
+H5FD__ros3_str_token_cmp(const void *_value1, const void *_value2, size_t H5_ATTR_UNUSED size)
+{
+    char *const *value1    = (char *const *)_value1;
+    char *const *value2    = (char *const *)_value2;
+    int          ret_value = SUCCEED;
+
+    FUNC_ENTER_PACKAGE_NOERR
+
+    if (*value1) {
+        if (*value2)
+            ret_value = HDstrcmp(*value1, *value2);
+        else
+            ret_value = 1;
+    }
+    else {
+        if (*value2)
+            ret_value = -1;
+        else
+            ret_value = 0;
+    }
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5FD__ros3_str_token_cmp */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD__ros3_str_token_close()
+ *
+ * Purpose:     Closes/frees the memory associated to the token string.
+ *              Currently, it is an empty implementation since there no
+ *              additional treatment needed for this property.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ * Programmer:  Jan-Willem Blokland
+ *              2023-05-26
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5FD__ros3_str_token_close(const char H5_ATTR_UNUSED *name, size_t H5_ATTR_UNUSED size, void *_value)
+{
+    char **value     = (char **)_value;
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_PACKAGE_NOERR
+
+    if (*value)
+        free(*value);
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5FD__ros3_str_token_close */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD__ros3_str_token_delete()
+ *
+ * Purpose:     Deletes the property token from the property list and frees
+ *              the memory associated to the token string.
+ *              Currently, it is an empty implementation since there no
+ *              additional treatment needed for this property.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ * Programmer:  Jan-Willem Blokland
+ *              2023-05-26
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5FD__ros3_str_token_delete(hid_t H5_ATTR_UNUSED prop_id, const char H5_ATTR_UNUSED *name,
+                            size_t H5_ATTR_UNUSED size, void *_value)
+{
+    char **value     = (char **)_value;
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_PACKAGE_NOERR
+
+    if (*value)
+        free(*value);
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5FD__ros3_str_token_delete */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Pset_fapl_ros3_token()
+ *
+ * Purpose:     Modify the file access property list to use the H5FD_ROS3
+ *              driver defined in this source file by adding or
+ *              modifying the session/security token property.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ * Programmer:  Jan-Willem Blokland
+ *              2023-05-26
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pset_fapl_ros3_token(hid_t fapl_id, const char *token)
+{
+    H5P_genplist_t *plist = NULL;
+    char           *token_src;
+    htri_t          token_exists;
+    herr_t          ret_value = SUCCEED;
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE2("e", "i*s", fapl_id, token);
+
+#if ROS3_DEBUG
+    fprintf(stdout, "H5Pset_fapl_ros3_token() called.\n");
+#endif
+
+    if (fapl_id == H5P_DEFAULT)
+        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")
+    if (NULL == (plist = H5P_object_verify(fapl_id, H5P_FILE_ACCESS)))
+        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a file access property list")
+    if (H5FD_ROS3 != H5P_peek_driver(plist))
+        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "incorrect VFL driver")
+    if (HDstrlen(token) > H5FD_ROS3_MAX_SECRET_TOK_LEN)
+        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL,
+                    "specified token exceeds the internally specified maximum string length")
+
+    if ((token_exists = H5P_exist_plist(plist, ROS3_TOKEN_PROP_NAME)) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "failed to check if property token exists in plist")
+
+    if (token_exists) {
+        if (H5P_get(plist, ROS3_TOKEN_PROP_NAME, &token_src) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get token value")
+
+        memcpy(token_src, token, HDstrlen(token) + 1);
+    }
+    else {
+        token_src = (char *)malloc(sizeof(char) * (H5FD_ROS3_MAX_SECRET_TOK_LEN + 1));
+        if (token_src == NULL)
+            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "cannot make space for token_src variable.");
+        memcpy(token_src, token, HDstrlen(token) + 1);
+        if (H5P_insert(plist, ROS3_TOKEN_PROP_NAME, sizeof(char *), &token_src, NULL, NULL, NULL, NULL,
+                       H5FD__ros3_str_token_delete, H5FD__ros3_str_token_copy, H5FD__ros3_str_token_cmp,
+                       H5FD__ros3_str_token_close) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTREGISTER, FAIL, "unable to register property in plist")
+    }
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pset_fapl_ros3_token() */
+
 #if ROS3_STATS
 /*----------------------------------------------------------------------------
  *
@@ -613,7 +868,7 @@ ros3_reset_stats(H5FD_ros3_t *file)
     }
 
 done:
-    FUNC_LEAVE_NOAPI(ret_value);
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end ros3_reset_stats() */
 #endif /* ROS3_STATS */
 
@@ -654,6 +909,9 @@ H5FD__ros3_open(const char *url, unsigned flags, hid_t fapl_id, haddr_t maxaddr)
     unsigned char    signing_key[SHA256_DIGEST_LENGTH];
     s3r_t           *handle = NULL;
     H5FD_ros3_fapl_t fa;
+    H5P_genplist_t  *plist = NULL;
+    htri_t           token_exists;
+    char            *token;
     H5FD_t          *ret_value = NULL;
 
     FUNC_ENTER_PACKAGE
@@ -681,6 +939,16 @@ H5FD__ros3_open(const char *url, unsigned flags, hid_t fapl_id, haddr_t maxaddr)
     if (CURLE_OK != curl_global_init(CURL_GLOBAL_DEFAULT))
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "unable to initialize curl global (placeholder flags)")
 
+    /* Session/security token */
+    if (NULL == (plist = H5P_object_verify(fapl_id, H5P_FILE_ACCESS)))
+        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, NULL, "not a file access property list")
+    if ((token_exists = H5P_exist_plist(plist, ROS3_TOKEN_PROP_NAME)) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "failed to check if property token exists in plist")
+    if (token_exists) {
+        if (H5P_get(plist, ROS3_TOKEN_PROP_NAME, &token) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "unable to get token value")
+    }
+
     /* open file; procedure depends on whether or not the fapl instructs to
      * authenticate requests or not.
      */
@@ -697,11 +965,15 @@ H5FD__ros3_open(const char *url, unsigned flags, hid_t fapl_id, haddr_t maxaddr)
                                              (const char *)fa.aws_region, (const char *)iso8601now))
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "problem while computing signing key")
 
-        handle = H5FD_s3comms_s3r_open(url, (const char *)fa.aws_region, (const char *)fa.secret_id,
-                                       (const unsigned char *)signing_key);
+        if (token_exists)
+            handle = H5FD_s3comms_s3r_open(url, (const char *)fa.aws_region, (const char *)fa.secret_id,
+                                           (const unsigned char *)signing_key, (const char *)token);
+        else
+            handle = H5FD_s3comms_s3r_open(url, (const char *)fa.aws_region, (const char *)fa.secret_id,
+                                           (const unsigned char *)signing_key, "");
     }
     else
-        handle = H5FD_s3comms_s3r_open(url, NULL, NULL, NULL);
+        handle = H5FD_s3comms_s3r_open(url, NULL, NULL, NULL, NULL);
 
     if (handle == NULL)
         /* If we want to check CURL's say on the matter in a controlled
@@ -729,7 +1001,7 @@ H5FD__ros3_open(const char *url, unsigned flags, hid_t fapl_id, haddr_t maxaddr)
     if (ret_value == NULL) {
         if (handle != NULL)
             if (FAIL == H5FD_s3comms_s3r_close(handle))
-                HDONE_ERROR(H5E_VFL, H5E_CANTCLOSEFILE, NULL, "unable to close s3 file handle")
+                HDONE_ERROR(H5E_VFL, H5E_CANTCLOSEFILE, NULL, "unable to close s3 file handle");
         if (file != NULL)
             file = H5FL_FREE(H5FD_ros3_t, file);
         curl_global_cleanup(); /* early cleanup because open failed */
@@ -1011,7 +1283,7 @@ ros3_fprint_stats(FILE *stream, const H5FD_ros3_t *file)
     }
 
 done:
-    FUNC_LEAVE_NOAPI(ret_value);
+    FUNC_LEAVE_NOAPI(ret_value)
 
 } /* ros3_fprint_stats */
 #endif /* ROS3_STATS */
@@ -1122,16 +1394,16 @@ H5FD__ros3_cmp(const H5FD_t *_f1, const H5FD_t *_f2)
 
     /* URL: SCHEME */
     if (HDstrcmp(purl1->scheme, purl2->scheme))
-        HGOTO_DONE(-1)
+        HGOTO_DONE(-1);
 
     /* URL: HOST */
     if (HDstrcmp(purl1->host, purl2->host))
-        HGOTO_DONE(-1)
+        HGOTO_DONE(-1);
 
     /* URL: PORT */
     if (purl1->port && purl2->port) {
         if (HDstrcmp(purl1->port, purl2->port))
-            HGOTO_DONE(-1)
+            HGOTO_DONE(-1);
     }
     else if (purl1->port)
         HGOTO_DONE(-1)
@@ -1141,7 +1413,7 @@ H5FD__ros3_cmp(const H5FD_t *_f1, const H5FD_t *_f2)
     /* URL: PATH */
     if (purl1->path && purl2->path) {
         if (HDstrcmp(purl1->path, purl2->path))
-            HGOTO_DONE(-1)
+            HGOTO_DONE(-1);
     }
     else if (purl1->path && !purl2->path)
         HGOTO_DONE(-1)
@@ -1151,7 +1423,7 @@ H5FD__ros3_cmp(const H5FD_t *_f1, const H5FD_t *_f2)
     /* URL: QUERY */
     if (purl1->query && purl2->query) {
         if (HDstrcmp(purl1->query, purl2->query))
-            HGOTO_DONE(-1)
+            HGOTO_DONE(-1);
     }
     else if (purl1->query && !purl2->query)
         HGOTO_DONE(-1)
@@ -1161,7 +1433,7 @@ H5FD__ros3_cmp(const H5FD_t *_f1, const H5FD_t *_f2)
     /* FAPL: AWS_REGION */
     if (f1->fa.aws_region[0] != '\0' && f2->fa.aws_region[0] != '\0') {
         if (HDstrcmp(f1->fa.aws_region, f2->fa.aws_region))
-            HGOTO_DONE(-1)
+            HGOTO_DONE(-1);
     }
     else if (f1->fa.aws_region[0] != '\0')
         HGOTO_DONE(-1)
@@ -1171,7 +1443,7 @@ H5FD__ros3_cmp(const H5FD_t *_f1, const H5FD_t *_f2)
     /* FAPL: SECRET_ID */
     if (f1->fa.secret_id[0] != '\0' && f2->fa.secret_id[0] != '\0') {
         if (HDstrcmp(f1->fa.secret_id, f2->fa.secret_id))
-            HGOTO_DONE(-1)
+            HGOTO_DONE(-1);
     }
     else if (f1->fa.secret_id[0] != '\0')
         HGOTO_DONE(-1)
@@ -1181,7 +1453,7 @@ H5FD__ros3_cmp(const H5FD_t *_f1, const H5FD_t *_f2)
     /* FAPL: SECRET_KEY */
     if (f1->fa.secret_key[0] != '\0' && f2->fa.secret_key[0] != '\0') {
         if (HDstrcmp(f1->fa.secret_key, f2->fa.secret_key))
-            HGOTO_DONE(-1)
+            HGOTO_DONE(-1);
     }
     else if (f1->fa.secret_key[0] != '\0')
         HGOTO_DONE(-1)
diff --git a/src/H5FDros3.h b/src/H5FDros3.h
index f84b1a44a6d..0f2f31538a0 100644
--- a/src/H5FDros3.h
+++ b/src/H5FDros3.h
@@ -70,12 +70,63 @@
  *
  ****************************************************************************/
 
+/**
+ * \def H5FD_CURR_ROS3_FAPL_T_VERSION
+ * The version number of the H5FD_ros3_fapl_t configuration
+ * structure for the $H5FD_ROS3 driver.
+ */
 #define H5FD_CURR_ROS3_FAPL_T_VERSION 1
 
-#define H5FD_ROS3_MAX_REGION_LEN     32
-#define H5FD_ROS3_MAX_SECRET_ID_LEN  128
+/**
+ * \def H5FD_ROS3_MAX_REGION_LEN
+ * Maximum string length for specifying the region of the S3 bucket.
+ */
+#define H5FD_ROS3_MAX_REGION_LEN 32
+/**
+ * \def H5FD_ROS3_MAX_SECRET_ID_LEN
+ * Maximum string length for specifying the security ID.
+ */
+#define H5FD_ROS3_MAX_SECRET_ID_LEN 128
+/**
+ * \def H5FD_ROS3_MAX_SECRET_KEY_LEN
+ * Maximum string length for specifying the security key.
+ */
 #define H5FD_ROS3_MAX_SECRET_KEY_LEN 128
+/**
+ * \def H5FD_ROS3_MAX_SECRET_TOK_LEN
+ * Maximum string length for specifying the session/security token.
+ */
+#define H5FD_ROS3_MAX_SECRET_TOK_LEN 1024
 
+/**
+ *\struct H5FD_ros3_fapl_t
+ * \brief Configuration structure for H5Pset_fapl_ros3() / H5Pget_fapl_ros3().
+ *
+ * \details H5FD_ros_fapl_t is a public structure that is used to pass
+ *          configuration data to the #H5FD_ROS3 driver via a File Access
+ *          Property List. A pointer to an instance of this structure is
+ *          a parameter to H5Pset_fapl_ros3() and H5Pget_fapl_ros3().
+ *
+ * \var int32_t H5FD_ros3_fapl_t::version
+ *      Version number of the H5FD_ros3_fapl_t structure. Any instance passed
+ *      to H5Pset_fapl_ros3() / H5Pget_fapl_ros3() must have a recognized version
+ *      number or an error will be raised. Currently, this field should be set
+ *      to #H5FD_CURR_ROS3_FAPL_T_VERSION.
+ *
+ * \var hbool_t H5FD_ros3_fapl_t::authenticate
+ *      A boolean which specifies if security credentials should be used for
+ *      accessing a S3 bucket.
+ *
+ * \var char H5FD_ros3_fapl_t::aws_region[H5FD_ROS3_MAX_REGION_LEN + 1]
+ *      A string which specifies the AWS region of the S3 bucket.
+ *
+ * \var char H5FD_ros3_fapl_t::secret_id[H5FD_ROS3_MAX_SECRET_ID_LEN + 1]
+ *      A string which specifies the security ID.
+ *
+ * \var char H5FD_ros3_fapl_t::secret_key[H5FD_ROS3_MAX_SECRET_KEY_LEN + 1]
+ *      A string which specifies the security key.
+ *
+ */
 typedef struct H5FD_ros3_fapl_t {
     int32_t version;
     hbool_t authenticate;
@@ -88,22 +139,72 @@ typedef struct H5FD_ros3_fapl_t {
 extern "C" {
 #endif
 
+/**
+ * \brief Internal routine to initialize #H5FD_ROS3 driver. Not meant to be
+ *        called directly by an HDF5 application.
+ */
 H5_DLL hid_t H5FD_ros3_init(void);
 
 /**
  * \ingroup FAPL
  *
- * \todo Add missing documentation
+ * \brief Queries a File Access Property List for #H5FD_ROS3 file driver properties.
+ *
+ * \fapl_id
+ * \param[out] fa_out Pointer to #H5FD_ROS3 driver configuration structure.
+ * \returns \herr_t
  */
 H5_DLL herr_t H5Pget_fapl_ros3(hid_t fapl_id, H5FD_ros3_fapl_t *fa_out);
 
 /**
  * \ingroup FAPL
  *
- * \todo Add missing documentation
+ * \brief Modifies the specified File Access Property List to use the #H5FD_ROS3 driver.
+ *
+ * \fapl_id
+ * \param[in] fa Pointer to #H5FD_ROS3 driver configuration structure.
+ * \returns \herr_t
  */
 H5_DLL herr_t H5Pset_fapl_ros3(hid_t fapl_id, const H5FD_ros3_fapl_t *fa);
 
+/**
+ * \ingroup FAPL
+ *
+ * \brief Queries a File Access Property List for #H5FD_ROS3 file driver session/security
+ *        token.
+ *
+ * \fapl_id
+ * \param[in] size Size of the provided char array for storing the session/security token.
+ * \param[out] token Session/security token.
+ * \returns \herr_t
+ *
+ * \since 1.14.2
+ */
+H5_DLL herr_t H5Pget_fapl_ros3_token(hid_t fapl_id, size_t size, char *token);
+
+/**
+ * \ingroup FAPL
+ *
+ * \brief Modifies the specified File Access Property List to use the #H5FD_ROS3 driver
+ *        by adding the specified session/security token.
+ *
+ * \fapl_id
+ * \param[in] token Session/security token.
+ * \returns \herr_t
+ *
+ * \details H5Pset_fapl_ros3_token() modifies an existing File Access Property List which
+ *          is used by #H5FD_ROS3 driver by adding or updating the session/security token
+ *          of the property list. Be aware, to set the token first you need to create
+ *          a proper File Access Property List using H5Pset_fapl_ros() and use this list
+ *          as input argument of the function H5Pset_fapl_ros3_token().
+ *
+ *          Note, the session token is only needed when you want to access a S3 bucket
+ *          using temporary security credentials.
+ *
+ * \since 1.14.2
+ */
+H5_DLL herr_t H5Pset_fapl_ros3_token(hid_t fapl_id, const char *token);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/H5FDs3comms.c b/src/H5FDs3comms.c
index d8be2a14027..5b697127dfe 100644
--- a/src/H5FDs3comms.c
+++ b/src/H5FDs3comms.c
@@ -39,6 +39,7 @@
 #include "H5Eprivate.h"  /* error handling    */
 #include "H5MMprivate.h" /* memory management */
 #include "H5FDs3comms.h" /* S3 Communications */
+#include "H5FDros3.h"    /* ros3 file driver  */
 
 /****************/
 /* Local Macros */
@@ -552,7 +553,7 @@ H5FD_s3comms_hrb_node_set(hrb_node_t **L, const char *name, const char *value)
         }
     }
 
-    FUNC_LEAVE_NOAPI(ret_value);
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD_s3comms_hrb_node_set() */
 
 /*----------------------------------------------------------------------------
@@ -775,6 +776,7 @@ H5FD_s3comms_s3r_close(s3r_t *handle)
     H5MM_xfree(handle->secret_id);
     H5MM_xfree(handle->region);
     H5MM_xfree(handle->signing_key);
+    H5MM_xfree(handle->token);
 
     assert(handle->httpverb != NULL);
     H5MM_xfree(handle->httpverb);
@@ -911,7 +913,7 @@ H5FD_s3comms_s3r_getsize(s3r_t *handle)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "No HTTP metadata")
 #if S3COMMS_DEBUG
     else
-        fprintf(stderr, "GETSIZE: OK\n");
+        fprintf(stdout, "GETSIZE: OK\n");
 #endif
 
     /******************
@@ -932,17 +934,21 @@ H5FD_s3comms_s3r_getsize(s3r_t *handle)
      */
     *end = '\0';
 
-    content_length = HDstrtoumax((const char *)start, NULL, 0);
+    content_length = strtoumax((const char *)start, NULL, 0);
     if (UINTMAX_MAX > SIZE_MAX && content_length > SIZE_MAX)
         HGOTO_ERROR(H5E_ARGS, H5E_OVERFLOW, FAIL, "content_length overflows size_t");
 
-    if (content_length == 0 || errno == ERANGE) /* errno set by HDstrtoumax*/
+    if (content_length == 0 || errno == ERANGE) /* errno set by strtoumax*/
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL,
                     "could not convert found \"Content-Length\" response (\"%s\")",
                     start); /* range is null-terminated, remember */
 
     handle->filesize = (size_t)content_length;
 
+#if S3COMMS_DEBUG
+    fprintf(stdout, "FILESIZE: %zu\n", handle->filesize);
+#endif
+
     /**********************
      * UNDO HEAD SETTINGS *
      **********************/
@@ -957,7 +963,7 @@ H5FD_s3comms_s3r_getsize(s3r_t *handle)
     H5MM_xfree(headerresponse);
     sds.magic += 1; /* set to bad magic */
 
-    FUNC_LEAVE_NOAPI(ret_value);
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* H5FD_s3comms_s3r_getsize */
 
 /*----------------------------------------------------------------------------
@@ -997,7 +1003,8 @@ H5FD_s3comms_s3r_getsize(s3r_t *handle)
  *----------------------------------------------------------------------------
  */
 s3r_t *
-H5FD_s3comms_s3r_open(const char *url, const char *region, const char *id, const unsigned char *signing_key)
+H5FD_s3comms_s3r_open(const char *url, const char *region, const char *id, const unsigned char *signing_key,
+                      const char *token)
 {
     size_t        tmplen    = 0;
     CURL         *curlh     = NULL;
@@ -1031,13 +1038,15 @@ H5FD_s3comms_s3r_open(const char *url, const char *region, const char *id, const
     handle->region      = NULL;
     handle->secret_id   = NULL;
     handle->signing_key = NULL;
+    handle->token       = NULL;
     handle->httpverb    = NULL;
 
     /*************************************
      * RECORD AUTHENTICATION INFORMATION *
      *************************************/
 
-    if ((region != NULL && *region != '\0') || (id != NULL && *id != '\0') || (signing_key != NULL)) {
+    if ((region != NULL && *region != '\0') || (id != NULL && *id != '\0') || (signing_key != NULL) ||
+        (token != NULL)) {
 
         /* if one exists, all three must exist */
         if (region == NULL || region[0] == '\0')
@@ -1046,6 +1055,8 @@ H5FD_s3comms_s3r_open(const char *url, const char *region, const char *id, const
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "secret id cannot be null.");
         if (signing_key == NULL)
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "signing key cannot be null.");
+        if (token == NULL)
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "token cannot be null.");
 
         /* copy strings */
         tmplen         = HDstrlen(region) + 1;
@@ -1065,6 +1076,12 @@ H5FD_s3comms_s3r_open(const char *url, const char *region, const char *id, const
         if (handle->signing_key == NULL)
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "could not malloc space for handle key copy.");
         H5MM_memcpy(handle->signing_key, signing_key, tmplen);
+
+        tmplen        = HDstrlen(token) + 1;
+        handle->token = (char *)H5MM_malloc(sizeof(char) * tmplen);
+        if (handle->token == NULL)
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "could not malloc space for handle token copy.");
+        H5MM_memcpy(handle->token, token, tmplen);
     } /* if authentication information provided */
 
     /************************
@@ -1121,11 +1138,12 @@ H5FD_s3comms_s3r_open(const char *url, const char *region, const char *id, const
         if (curlh != NULL)
             curl_easy_cleanup(curlh);
         if (FAIL == H5FD_s3comms_free_purl(purl))
-            HDONE_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "unable to free parsed url structure")
+            HDONE_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "unable to free parsed url structure");
         if (handle != NULL) {
             H5MM_xfree(handle->region);
             H5MM_xfree(handle->secret_id);
             H5MM_xfree(handle->signing_key);
+            H5MM_xfree(handle->token);
             if (handle->httpverb != NULL)
                 H5MM_xfree(handle->httpverb);
             H5MM_xfree(handle);
@@ -1186,8 +1204,11 @@ H5FD_s3comms_s3r_read(s3r_t *handle, haddr_t offset, size_t len, void *dest)
     hrb_t             *request       = NULL;
     int                ret           = 0; /* working variable to check  */
                                           /* return value of HDsnprintf  */
-    struct s3r_datastruct *sds       = NULL;
-    herr_t                 ret_value = SUCCEED;
+    char                  *authorization  = NULL;
+    char                  *buffer1        = NULL;
+    char                  *signed_headers = NULL;
+    struct s3r_datastruct *sds            = NULL;
+    herr_t                 ret_value      = SUCCEED;
 
     FUNC_ENTER_NOAPI_NOINIT
 
@@ -1252,6 +1273,11 @@ H5FD_s3comms_s3r_read(s3r_t *handle, haddr_t offset, size_t len, void *dest)
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unable to format HTTP Range value");
     }
 
+#if S3COMMS_DEBUG
+    fprintf(stdout, "%s: Bytes %" PRIuHADDR " - %" PRIuHADDR ", Request Size: %zu\n", handle->httpverb,
+            offset, offset + len - 1, len);
+#endif
+
     /*******************
      * COMPILE REQUEST *
      *******************/
@@ -1275,23 +1301,31 @@ H5FD_s3comms_s3r_read(s3r_t *handle, haddr_t offset, size_t len, void *dest)
     else {
         /* authenticate request
          */
-        char authorization[512 + 1];
-        /*   512 := approximate max length...
-         *    67 <len("AWS4-HMAC-SHA256 Credential=///s3/aws4_request,"
-         *           "SignedHeaders=,Signature=")>
-         * +   8 <yyyyMMDD>
-         * +  64 <hex(sha256())>
-         * + 128 <max? len(secret_id)>
-         * +  20 <max? len(region)>
-         * + 128 <max? len(signed_headers)>
+        authorization = (char *)H5MM_malloc(512 + H5FD_ROS3_MAX_SECRET_TOK_LEN + 1);
+        if (authorization == NULL)
+            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "cannot make space for authorization variable.");
+        /*   2048 := approximate max length...
+         *     67 <len("AWS4-HMAC-SHA256 Credential=///s3/aws4_request,"
+         *             "SignedHeaders=,Signature=")>
+         * +    8 <yyyyMMDD>
+         * +   64 <hex(sha256())>
+         * +  128 <max? len(secret_id)>
+         * +   20 <max? len(region)>
+         * +  128 <max? len(signed_headers)>
+         * + 1024 <max? len(session_token)>
          */
-        char buffer1[512 + 1]; /* -> Canonical Request -> Signature */
         char buffer2[256 + 1]; /* -> String To Sign -> Credential */
         char iso8601now[ISO8601_SIZE];
-        char signed_headers[48 + 1];
+        buffer1 = (char *)H5MM_malloc(512 + H5FD_ROS3_MAX_SECRET_TOK_LEN +
+                                      1); /* -> Canonical Request -> Signature */
+        if (buffer1 == NULL)
+            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "cannot make space for buffer1 variable.");
+        signed_headers = (char *)H5MM_malloc(48 + H5FD_ROS3_MAX_SECRET_KEY_LEN + 1);
+        if (signed_headers == NULL)
+            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "cannot make space for signed_headers variable.");
         /* should be large enough for nominal listing:
-         * "host;range;x-amz-content-sha256;x-amz-date"
-         * + '\0', with "range;" possibly absent
+         * "host;range;x-amz-content-sha256;x-amz-date;x-amz-security-token"
+         * + '\0', with "range;" and/or "x-amz-security-token" possibly absent
          */
 
         /* zero start of strings */
@@ -1309,6 +1343,8 @@ H5FD_s3comms_s3r_read(s3r_t *handle, haddr_t offset, size_t len, void *dest)
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "handle must have non-null secret_id.");
         if (handle->signing_key == NULL)
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "handle must have non-null signing_key.");
+        if (handle->token == NULL)
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "handle must have non-null token.");
         if (handle->httpverb == NULL)
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "handle must have non-null httpverb.");
         if (handle->purl->host == NULL)
@@ -1340,6 +1376,15 @@ H5FD_s3comms_s3r_read(s3r_t *handle, haddr_t offset, size_t len, void *dest)
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "problem building headers list.");
         assert(headers->magic == S3COMMS_HRB_NODE_MAGIC);
 
+        if (HDstrlen((const char *)handle->token) > 0) {
+            if (FAIL ==
+                H5FD_s3comms_hrb_node_set(&headers, "x-amz-security-token", (const char *)handle->token))
+                HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unable to set x-amz-security-token header")
+            if (headers == NULL)
+                HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "problem building headers list.");
+            assert(headers->magic == S3COMMS_HRB_NODE_MAGIC);
+        }
+
         if (rangebytesstr != NULL) {
             if (FAIL == H5FD_s3comms_hrb_node_set(&headers, "Range", rangebytesstr))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unable to set range header")
@@ -1359,8 +1404,11 @@ H5FD_s3comms_s3r_read(s3r_t *handle, haddr_t offset, size_t len, void *dest)
         /**** COMPUTE AUTHORIZATION ****/
 
         /* buffer1 -> canonical request */
-        if (FAIL == H5FD_s3comms_aws_canonical_request(buffer1, 512, signed_headers, 48, request))
+        if (FAIL == H5FD_s3comms_aws_canonical_request(buffer1, 512 + H5FD_ROS3_MAX_SECRET_TOK_LEN,
+                                                       signed_headers, 48 + H5FD_ROS3_MAX_SECRET_TOK_LEN,
+                                                       request)) {
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "bad canonical request");
+        }
         /* buffer2->string-to-sign */
         if (FAIL == H5FD_s3comms_tostringtosign(buffer2, buffer1, iso8601now, handle->region))
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "bad string-to-sign");
@@ -1374,9 +1422,10 @@ H5FD_s3comms_s3r_read(s3r_t *handle, haddr_t offset, size_t len, void *dest)
         if (ret == 0 || ret >= S3COMMS_MAX_CREDENTIAL_SIZE)
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unable to format aws4 credential string");
 
-        ret = HDsnprintf(authorization, 512, "AWS4-HMAC-SHA256 Credential=%s,SignedHeaders=%s,Signature=%s",
-                         buffer2, signed_headers, buffer1);
-        if (ret <= 0 || ret >= 512)
+        ret = HDsnprintf(authorization, 512 + H5FD_ROS3_MAX_SECRET_TOK_LEN,
+                         "AWS4-HMAC-SHA256 Credential=%s,SignedHeaders=%s,Signature=%s", buffer2,
+                         signed_headers, buffer1);
+        if (ret <= 0 || ret >= 512 + H5FD_ROS3_MAX_SECRET_TOK_LEN)
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unable to format aws4 authorization string");
 
         /* append authorization header to http request buffer */
@@ -1431,8 +1480,9 @@ H5FD_s3comms_s3r_read(s3r_t *handle, haddr_t offset, size_t len, void *dest)
         if (p_status != CURLE_OK) {
             if (CURLE_OK != curl_easy_getinfo(curlh, CURLINFO_RESPONSE_CODE, &httpcode))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "problem getting response code")
-            fprintf(stderr, "CURL ERROR CODE: %d\nHTTP CODE: %d\n", p_status, httpcode);
-            fprintf(stderr, "%s\n", curl_easy_strerror(p_status));
+            fprintf(stdout, "CURL ERROR CODE: %d\nHTTP CODE: %ld\n", p_status, httpcode);
+            fprintf(stdout, "%s\n", curl_easy_strerror(p_status));
+
             HGOTO_ERROR(H5E_VFL, H5E_CANTOPENFILE, FAIL, "problem while performing request.");
         }
         if (CURLE_OK != curl_easy_setopt(curlh, CURLOPT_ERRORBUFFER, NULL))
@@ -1447,24 +1497,36 @@ H5FD_s3comms_s3r_read(s3r_t *handle, haddr_t offset, size_t len, void *dest)
 
 #if S3COMMS_DEBUG
     if (dest != NULL) {
-        fprintf(stderr, "len: %d\n", (int)len);
-        fprintf(stderr, "CHECKING FOR BUFFER OVERFLOW\n");
+        fprintf(stdout, "len: %d\n", (int)len);
+        fprintf(stdout, "CHECKING FOR BUFFER OVERFLOW\n");
         if (sds == NULL)
-            fprintf(stderr, "sds is NULL!\n");
+            fprintf(stdout, "sds is NULL!\n");
         else {
-            fprintf(stderr, "sds: 0x%lx\n", (long long)sds);
-            fprintf(stderr, "sds->size: %d\n", (int)sds->size);
+            fprintf(stdout, "sds: 0x%llx\n", (long long)sds);
+            fprintf(stdout, "sds->size: %d\n", (int)sds->size);
             if (len > sds->size)
-                fprintf(stderr, "buffer overwrite\n");
+                fprintf(stdout, "buffer overwrite\n");
         }
     }
     else
-        fprintf(stderr, "performed on entire file\n");
+        fprintf(stdout, "performed on entire file\n");
 #endif
 
 done:
     /* clean any malloc'd resources
      */
+    if (authorization != NULL) {
+        H5MM_xfree(authorization);
+        authorization = NULL;
+    }
+    if (buffer1 != NULL) {
+        H5MM_xfree(buffer1);
+        buffer1 = NULL;
+    }
+    if (signed_headers != NULL) {
+        H5MM_xfree(signed_headers);
+        signed_headers = NULL;
+    }
     if (curlheaders != NULL) {
         curl_slist_free_all(curlheaders);
         curlheaders = NULL;
@@ -1480,24 +1542,24 @@ H5FD_s3comms_s3r_read(s3r_t *handle, haddr_t offset, size_t len, void *dest)
     if (request != NULL) {
         while (headers != NULL)
             if (FAIL == H5FD_s3comms_hrb_node_set(&headers, headers->name, NULL))
-                HDONE_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "cannot release header node")
+                HDONE_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "cannot release header node");
         assert(NULL == headers);
         if (FAIL == H5FD_s3comms_hrb_destroy(&request))
-            HDONE_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "cannot release header request structure")
+            HDONE_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "cannot release header request structure");
         assert(NULL == request);
     }
 
     if (curlh != NULL) {
         /* clear any Range */
         if (CURLE_OK != curl_easy_setopt(curlh, CURLOPT_RANGE, NULL))
-            HDONE_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "cannot unset CURLOPT_RANGE")
+            HDONE_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "cannot unset CURLOPT_RANGE");
 
         /* clear headers */
         if (CURLE_OK != curl_easy_setopt(curlh, CURLOPT_HTTPHEADER, NULL))
-            HDONE_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "cannot unset CURLOPT_HTTPHEADER")
+            HDONE_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "cannot unset CURLOPT_HTTPHEADER");
     }
 
-    FUNC_LEAVE_NOAPI(ret_value);
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* H5FD_s3comms_s3r_read */
 
 /****************************************************************************
@@ -1583,8 +1645,7 @@ H5FD_s3comms_aws_canonical_request(char *canonical_request_dest, int _cr_size, c
     size_t      sh_size      = (size_t)_sh_size;
     size_t      cr_len       = 0; /* working length of canonical request str */
     size_t      sh_len       = 0; /* working length of signed headers str */
-    char        tmpstr[256 + 1];
-    tmpstr[256] = 0; /* terminating NULL */
+    char        tmpstr[1024];
 
     /* "query params" refers to the optional element in the URL, e.g.
      *     http://bucket.aws.com/myfile.txt?max-keys=2&prefix=J
@@ -1617,6 +1678,7 @@ H5FD_s3comms_aws_canonical_request(char *canonical_request_dest, int _cr_size, c
               (size_t)3); /* three newline chars */
     if (cr_len >= cr_size)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "not enough space in canonical request");
+
     /* TODO: compiler warning */
     ret = HDsnprintf(canonical_request_dest, (cr_size - 1), "%s\n%s\n%s\n", http_request->verb,
                      http_request->resource, query_params);
@@ -1629,8 +1691,8 @@ H5FD_s3comms_aws_canonical_request(char *canonical_request_dest, int _cr_size, c
 
         assert(node->magic == S3COMMS_HRB_NODE_MAGIC);
 
-        ret = HDsnprintf(tmpstr, 256, "%s:%s\n", node->lowername, node->value);
-        if (ret < 0 || ret >= 256)
+        ret = HDsnprintf(tmpstr, 1024, "%s:%s\n", node->lowername, node->value);
+        if (ret < 0 || ret >= 1024)
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unable to concatenate HTTP header %s:%s",
                         node->lowername, node->value);
         cr_len += HDstrlen(tmpstr);
@@ -1638,8 +1700,8 @@ H5FD_s3comms_aws_canonical_request(char *canonical_request_dest, int _cr_size, c
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "not enough space in canonical request");
         HDstrcat(canonical_request_dest, tmpstr);
 
-        ret = HDsnprintf(tmpstr, 256, "%s;", node->lowername);
-        if (ret < 0 || ret >= 256)
+        ret = HDsnprintf(tmpstr, 1024, "%s;", node->lowername);
+        if (ret < 0 || ret >= 1024)
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unable to append semicolon to lowername %s",
                         node->lowername);
         sh_len += HDstrlen(tmpstr);
@@ -1663,7 +1725,7 @@ H5FD_s3comms_aws_canonical_request(char *canonical_request_dest, int _cr_size, c
     HDstrcat(canonical_request_dest, EMPTY_SHA256);
 
 done:
-    FUNC_LEAVE_NOAPI(ret_value);
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD_s3comms_aws_canonical_request() */
 
 /*----------------------------------------------------------------------------
@@ -1719,7 +1781,7 @@ H5FD_s3comms_bytes_to_hex(char *dest, const unsigned char *msg, size_t msg_len,
     }
 
 done:
-    FUNC_LEAVE_NOAPI(ret_value);
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD_s3comms_bytes_to_hex() */
 
 /*----------------------------------------------------------------------------
@@ -1816,7 +1878,7 @@ H5FD_s3comms_HMAC_SHA256(const unsigned char *key, size_t key_len, const char *m
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "could not convert to hex string.");
 
 done:
-    FUNC_LEAVE_NOAPI(ret_value);
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* H5FD_s3comms_HMAC_SHA256 */
 
 /*-----------------------------------------------------------------------------
@@ -1953,7 +2015,7 @@ H5FD__s3comms_load_aws_creds_from_file(FILE *file, const char *profile_name, cha
 
                 /* "trim" tailing whitespace by replacing with null terminator*/
                 buffer_i = 0;
-                while (!HDisspace(setting_pointers[setting_i][buffer_i]))
+                while (!isspace(setting_pointers[setting_i][buffer_i]))
                     buffer_i++;
                 setting_pointers[setting_i][buffer_i] = '\0';
 
@@ -1963,7 +2025,7 @@ H5FD__s3comms_load_aws_creds_from_file(FILE *file, const char *profile_name, cha
     } while (found_setting);
 
 done:
-    FUNC_LEAVE_NOAPI(ret_value);
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD__s3comms_load_aws_creds_from_file() */
 
 /*----------------------------------------------------------------------------
@@ -2027,7 +2089,7 @@ H5FD_s3comms_load_aws_profile(const char *profile_name, char *key_id_out, char *
         if (H5FD__s3comms_load_aws_creds_from_file(credfile, profile_name, key_id_out, secret_access_key_out,
                                                    aws_region_out) == FAIL)
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unable to load from aws credentials")
-        if (HDfclose(credfile) == EOF)
+        if (fclose(credfile) == EOF)
             HGOTO_ERROR(H5E_FILE, H5E_CANTCLOSEFILE, FAIL, "unable to close credentials file")
         credfile = NULL;
     } /* end if credential file opened */
@@ -2042,7 +2104,7 @@ H5FD_s3comms_load_aws_profile(const char *profile_name, char *key_id_out, char *
                 (*secret_access_key_out == 0) ? secret_access_key_out : NULL,
                 (*aws_region_out == 0) ? aws_region_out : NULL) == FAIL)
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "unable to load from aws config")
-        if (HDfclose(credfile) == EOF)
+        if (fclose(credfile) == EOF)
             HGOTO_ERROR(H5E_FILE, H5E_CANTCLOSEFILE, FAIL, "unable to close config file")
         credfile = NULL;
     } /* end if credential file opened */
@@ -2053,10 +2115,10 @@ H5FD_s3comms_load_aws_profile(const char *profile_name, char *key_id_out, char *
 
 done:
     if (credfile != NULL)
-        if (HDfclose(credfile) == EOF)
-            HDONE_ERROR(H5E_ARGS, H5E_ARGS, FAIL, "problem error-closing aws configuration file")
+        if (fclose(credfile) == EOF)
+            HDONE_ERROR(H5E_ARGS, H5E_ARGS, FAIL, "problem error-closing aws configuration file");
 
-    FUNC_LEAVE_NOAPI(ret_value);
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD_s3comms_load_aws_profile() */
 
 /*----------------------------------------------------------------------------
@@ -2105,7 +2167,7 @@ H5FD_s3comms_nlowercase(char *dest, const char *s, size_t len)
     }
 
 done:
-    FUNC_LEAVE_NOAPI(ret_value);
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD_s3comms_nlowercase() */
 
 /*----------------------------------------------------------------------------
@@ -2147,7 +2209,7 @@ H5FD_s3comms_parse_url(const char *str, parsed_url_t **_purl)
     unsigned int  i         = 0;
     herr_t        ret_value = FAIL;
 
-    FUNC_ENTER_NOAPI_NOINIT;
+    FUNC_ENTER_NOAPI_NOINIT
 
 #if S3COMMS_DEBUG
     printf("called H5FD_s3comms_parse_url.\n");
@@ -2181,7 +2243,7 @@ H5FD_s3comms_parse_url(const char *str, parsed_url_t **_purl)
     /* check for restrictions */
     for (i = 0; i < len; i++) {
         /* scheme = [a-zA-Z+-.]+ (terminated by ":") */
-        if (!HDisalpha(curstr[i]) && '+' != curstr[i] && '-' != curstr[i] && '.' != curstr[i])
+        if (!isalpha(curstr[i]) && '+' != curstr[i] && '-' != curstr[i] && '.' != curstr[i])
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid SCHEME construction");
     }
 
@@ -2247,7 +2309,7 @@ H5FD_s3comms_parse_url(const char *str, parsed_url_t **_purl)
         else if (len > urllen)
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "problem with length of PORT substring");
         for (i = 0; i < len; i++)
-            if (!HDisdigit(curstr[i]))
+            if (!isdigit(curstr[i]))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "PORT is not a decimal string");
 
         /* copy port */
@@ -2310,7 +2372,7 @@ H5FD_s3comms_parse_url(const char *str, parsed_url_t **_purl)
     if (ret_value == FAIL)
         H5FD_s3comms_free_purl(purl);
 
-    FUNC_LEAVE_NOAPI(ret_value);
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD_s3comms_parse_url() */
 
 /*----------------------------------------------------------------------------
@@ -2457,7 +2519,7 @@ H5FD_s3comms_percent_encode_char(char *repr, const unsigned char c, size_t *repr
     *(repr + *repr_len) = '\0';
 
 done:
-    FUNC_LEAVE_NOAPI(ret_value);
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* H5FD_s3comms_percent_encode_char */
 
 /*----------------------------------------------------------------------------
@@ -2547,7 +2609,7 @@ H5FD_s3comms_signing_key(unsigned char *md, const char *secret, const char *regi
 done:
     H5MM_xfree(AWS4_secret);
 
-    FUNC_LEAVE_NOAPI(ret_value);
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD_s3comms_signing_key() */
 
 /*----------------------------------------------------------------------------
@@ -2694,7 +2756,7 @@ H5FD_s3comms_trim(char *dest, char *s, size_t s_len, size_t *n_written)
         /* Find first non-whitespace character from start;
          * reduce total length per character.
          */
-        while ((s_len > 0) && HDisspace((unsigned char)s[0]) && s_len > 0) {
+        while ((s_len > 0) && isspace((unsigned char)s[0]) && s_len > 0) {
             s++;
             s_len--;
         }
@@ -2706,7 +2768,7 @@ H5FD_s3comms_trim(char *dest, char *s, size_t s_len, size_t *n_written)
         if (s_len > 0) {
             do {
                 s_len--;
-            } while (HDisspace((unsigned char)s[s_len]));
+            } while (isspace((unsigned char)s[s_len]));
             s_len++;
 
             /* write output into dest */
@@ -2783,8 +2845,7 @@ H5FD_s3comms_uriencode(char *dest, const char *s, size_t s_len, hbool_t encode_s
      */
     for (s_off = 0; s_off < s_len; s_off++) {
         c = s[s_off];
-        if (HDisalnum(c) || c == '.' || c == '-' || c == '_' || c == '~' ||
-            (c == '/' && encode_slash == FALSE))
+        if (isalnum(c) || c == '.' || c == '-' || c == '_' || c == '~' || (c == '/' && encode_slash == FALSE))
             dest[dest_off++] = c;
         else {
             hex_off = 0;
diff --git a/src/H5FDs3comms.h b/src/H5FDs3comms.h
index 1b21ad7510d..47857f66fbe 100644
--- a/src/H5FDs3comms.h
+++ b/src/H5FDs3comms.h
@@ -478,6 +478,7 @@ typedef struct {
     char          *region;
     char          *secret_id;
     unsigned char *signing_key;
+    char          *token;
 } s3r_t;
 
 #define S3COMMS_S3R_MAGIC 0x44d8d79
@@ -509,7 +510,7 @@ H5_DLL herr_t H5FD_s3comms_s3r_close(s3r_t *handle);
 H5_DLL size_t H5FD_s3comms_s3r_get_filesize(s3r_t *handle);
 
 H5_DLL s3r_t *H5FD_s3comms_s3r_open(const char url[], const char region[], const char id[],
-                                    const unsigned char signing_key[]);
+                                    const unsigned char signing_key[], const char token[]);
 
 H5_DLL herr_t H5FD_s3comms_s3r_read(s3r_t *handle, haddr_t offset, size_t len, void *dest);
 
diff --git a/test/ros3.c b/test/ros3.c
index 9a41a54d1c4..ab77d937528 100644
--- a/test/ros3.c
+++ b/test/ros3.c
@@ -549,7 +549,7 @@ test_fapl_config_validation(void)
              */
             success = H5Pset_fapl_ros3(fapl_id, &case_ptr->config);
         }
-        H5E_END_TRY;
+        H5E_END_TRY
 
         JSVERIFY(case_ptr->expected, success, case_ptr->msg)
 
@@ -590,7 +590,7 @@ test_fapl_config_validation(void)
         {
             (void)H5Pclose(fapl_id);
         }
-        H5E_END_TRY;
+        H5E_END_TRY
     }
     return 1;
 } /* test_fapl_config_validation */
@@ -664,7 +664,7 @@ test_ros3_fapl(void)
     {
         (void)H5Pclose(fapl_id);
     }
-    H5E_END_TRY;
+    H5E_END_TRY
 
     return 1;
 
@@ -832,7 +832,7 @@ test_vfd_open(void)
         {
             fd = H5FDopen(T.url, T.flags, _fapl_id, T.maxaddr);
         }
-        H5E_END_TRY;
+        H5E_END_TRY
         if (NULL != fd)
             JSVERIFY(1, 0, T.message); /* wrapper to print message and fail */
     }
@@ -876,14 +876,14 @@ test_vfd_open(void)
         {
             (void)H5Pclose(fapl_id);
         }
-        H5E_END_TRY;
+        H5E_END_TRY
     }
     if (fapl_file_access >= 0) {
         H5E_BEGIN_TRY
         {
             (void)H5Pclose(fapl_file_access);
         }
-        H5E_END_TRY;
+        H5E_END_TRY
     }
     if (curl_ready == TRUE) {
         curl_global_cleanup();
@@ -1014,7 +1014,7 @@ test_eof_eoa(void)
         {
             (void)H5Pclose(fapl_id);
         }
-        H5E_END_TRY;
+        H5E_END_TRY
     }
 
     return 1;
@@ -1078,17 +1078,17 @@ test_H5FDread_without_eoa_set_fails(void)
      * TEST *
      ********/
 
-    H5E_BEGIN_TRY{/* mute stack trace on expected failure */
-                  JSVERIFY(FAIL, H5FDread(file_shakespeare, H5FD_MEM_DRAW, H5P_DEFAULT, 1200699, 102, buffer),
-                           "cannot read before eoa is set")} H5E_END_TRY;
-    JSVERIFY_STR("", buffer, "buffer should remain untouched")
+    H5E_BEGIN_TRY{
+        /* mute stack trace on expected failure */
+        JSVERIFY(FAIL, H5FDread(file_shakespeare, H5FD_MEM_DRAW, H5P_DEFAULT, 1200699, 102, buffer),
+                 "cannot read before eoa is set")} H5E_END_TRY JSVERIFY_STR("", buffer,
+                                                                            "buffer should remain untouched")
 
-    /************
-     * TEARDOWN *
-     ************/
+        /************
+         * TEARDOWN *
+         ************/
 
-    FAIL_IF(FAIL == H5FDclose(file_shakespeare))
-    file_shakespeare = NULL;
+        FAIL_IF(FAIL == H5FDclose(file_shakespeare)) file_shakespeare = NULL;
 
     FAIL_IF(FAIL == H5Pclose(fapl_id))
     fapl_id = -1;
@@ -1109,7 +1109,7 @@ test_H5FDread_without_eoa_set_fails(void)
         {
             (void)H5Pclose(fapl_id);
         }
-        H5E_END_TRY;
+        H5E_END_TRY
     }
 
     return 1;
@@ -1276,7 +1276,7 @@ test_read(void)
         {
             open_return = H5FDread(file_raven, H5FD_MEM_DRAW, H5P_DEFAULT, test.addr, test.len, buffer);
         }
-        H5E_END_TRY;
+        H5E_END_TRY
 
         JSVERIFY(test.success, open_return, test.message)
         if (open_return == SUCCEED)
@@ -1309,7 +1309,7 @@ test_read(void)
         {
             (void)H5Pclose(fapl_id);
         }
-        H5E_END_TRY;
+        H5E_END_TRY
     }
 
     return 1;
@@ -1386,19 +1386,19 @@ test_noops_and_autofails(void)
     /* auto-fail calls to write and truncate
      */
     H5E_BEGIN_TRY{JSVERIFY(FAIL, H5FDwrite(file, H5FD_MEM_DRAW, H5P_DEFAULT, 1000, 35, data),
-                           "write must fail")} H5E_END_TRY;
+                           "write must fail")} H5E_END_TRY
 
-    H5E_BEGIN_TRY{JSVERIFY(FAIL, H5FDtruncate(file, H5P_DEFAULT, FALSE), "truncate must fail")} H5E_END_TRY;
+        H5E_BEGIN_TRY{
+            JSVERIFY(FAIL, H5FDtruncate(file, H5P_DEFAULT, FALSE), "truncate must fail")} H5E_END_TRY
 
-    H5E_BEGIN_TRY{
-        JSVERIFY(FAIL, H5FDtruncate(file, H5P_DEFAULT, TRUE), "truncate must fail (closing)")} H5E_END_TRY;
+            H5E_BEGIN_TRY{JSVERIFY(FAIL, H5FDtruncate(file, H5P_DEFAULT, TRUE),
+                                   "truncate must fail (closing)")} H5E_END_TRY
 
-    /************
-     * TEARDOWN *
-     ************/
+                /************
+                 * TEARDOWN *
+                 ************/
 
-    FAIL_IF(FAIL == H5FDclose(file))
-    file = NULL;
+                FAIL_IF(FAIL == H5FDclose(file)) file = NULL;
 
     FAIL_IF(FAIL == H5Pclose(fapl_id))
     fapl_id = -1;
@@ -1419,7 +1419,7 @@ test_noops_and_autofails(void)
         {
             (void)H5Pclose(fapl_id);
         }
-        H5E_END_TRY;
+        H5E_END_TRY
     }
     if (file) {
         (void)H5FDclose(file);
@@ -1550,7 +1550,7 @@ test_cmp(void)
         {
             (void)H5Pclose(fapl_id);
         }
-        H5E_END_TRY;
+        H5E_END_TRY
     }
 
     return 1;
@@ -1620,15 +1620,15 @@ test_H5F_integration(void)
 
     /* Read-Write Open access is not allowed with this file driver.
      */
-    H5E_BEGIN_TRY{FAIL_IF(0 <= H5Fopen(url_h5_public, H5F_ACC_RDWR, fapl_id))} H5E_END_TRY;
+    H5E_BEGIN_TRY{FAIL_IF(0 <= H5Fopen(url_h5_public, H5F_ACC_RDWR, fapl_id))} H5E_END_TRY
 
-    /* H5Fcreate() is not allowed with this file driver.
-     */
-    H5E_BEGIN_TRY{FAIL_IF(0 <= H5Fcreate(url_missing, H5F_ACC_RDONLY, H5P_DEFAULT, fapl_id))} H5E_END_TRY;
+        /* H5Fcreate() is not allowed with this file driver.
+         */
+        H5E_BEGIN_TRY{FAIL_IF(0 <= H5Fcreate(url_missing, H5F_ACC_RDONLY, H5P_DEFAULT, fapl_id))} H5E_END_TRY
 
-    /* Successful open.
-     */
-    file = H5Fopen(url_h5_public, H5F_ACC_RDONLY, fapl_id);
+            /* Successful open.
+             */
+            file = H5Fopen(url_h5_public, H5F_ACC_RDONLY, fapl_id);
     FAIL_IF(file < 0)
 
     /************
@@ -1656,7 +1656,7 @@ test_H5F_integration(void)
         {
             (void)H5Pclose(fapl_id);
         }
-        H5E_END_TRY;
+        H5E_END_TRY
     }
     if (file > 0)
         (void)H5Fclose(file);
diff --git a/test/s3comms.c b/test/s3comms.c
index 7307673d2a3..ea32769967a 100644
--- a/test/s3comms.c
+++ b/test/s3comms.c
@@ -348,6 +348,7 @@ static int     s3_test_credentials_loaded               = 0;
 static char    s3_test_aws_region[16]                   = "";
 static char    s3_test_aws_access_key_id[64]            = "";
 static char    s3_test_aws_secret_access_key[128]       = "";
+static char    s3_test_aws_security_token[1024]         = "";
 static char    s3_test_bucket_url[S3_TEST_MAX_URL_SIZE] = "";
 static hbool_t s3_test_bucket_defined                   = FALSE;
 
@@ -1692,10 +1693,7 @@ test_percent_encode_char(void)
 } /* end test_percent_encode_char() */
 
 /*---------------------------------------------------------------------------
- * Function: test_s3r_open()
- *
- * Programmer: Jacob Smith 2018-01-24
- *
+ * Function: test_s3r_get_filesize()
  *---------------------------------------------------------------------------
  */
 static herr_t
@@ -1725,7 +1723,7 @@ test_s3r_get_filesize(void)
 
     JSVERIFY(0, H5FD_s3comms_s3r_get_filesize(NULL), "filesize of the null handle should be 0")
 
-    handle = H5FD_s3comms_s3r_open(url_raven, NULL, NULL, NULL);
+    handle = H5FD_s3comms_s3r_open(url_raven, NULL, NULL, NULL, NULL);
     FAIL_IF(handle == NULL)
 
     JSVERIFY(6464, H5FD_s3comms_s3r_get_filesize(handle), NULL)
@@ -1833,14 +1831,14 @@ test_s3r_open(void)
 
     /* attempt anonymously
      */
-    handle = H5FD_s3comms_s3r_open(url_missing, NULL, NULL, NULL);
+    handle = H5FD_s3comms_s3r_open(url_missing, NULL, NULL, NULL, NULL);
     FAIL_IF(handle != NULL);
 
     /* attempt with authentication
      */
-    handle =
-        H5FD_s3comms_s3r_open(url_missing, (const char *)s3_test_aws_region,
-                              (const char *)s3_test_aws_access_key_id, (const unsigned char *)signing_key);
+    handle = H5FD_s3comms_s3r_open(
+        url_missing, (const char *)s3_test_aws_region, (const char *)s3_test_aws_access_key_id,
+        (const unsigned char *)signing_key, (const char *)s3_test_aws_security_token);
     FAIL_IF(handle != NULL);
 
     /*************************
@@ -1849,7 +1847,7 @@ test_s3r_open(void)
 
 #if S3_TEST_RUN_TIMEOUT
     printf("Opening on inactive port may hang for a minute; waiting for timeout\n");
-    handle = H5FD_s3comms_s3r_open(url_raven_badport, NULL, NULL, NULL);
+    handle = H5FD_s3comms_s3r_open(url_raven_badport, NULL, NULL, NULL, NULL);
     FAIL_IF(handle != NULL);
 #endif
 
@@ -1859,20 +1857,21 @@ test_s3r_open(void)
 
     /* anonymous access on restricted file
      */
-    handle = H5FD_s3comms_s3r_open(url_shakespeare, NULL, NULL, NULL);
+    handle = H5FD_s3comms_s3r_open(url_shakespeare, NULL, NULL, NULL, NULL);
     FAIL_IF(handle != NULL);
 
     /* passed in a bad ID
      */
-    handle = H5FD_s3comms_s3r_open(url_shakespeare, (const char *)s3_test_aws_region, "I_MADE_UP_MY_ID",
-                                   (const unsigned char *)signing_key);
+    handle =
+        H5FD_s3comms_s3r_open(url_shakespeare, (const char *)s3_test_aws_region, "I_MADE_UP_MY_ID",
+                              (const unsigned char *)signing_key, (const char *)s3_test_aws_security_token);
     FAIL_IF(handle != NULL);
 
     /* using an invalid signing key
      */
-    handle =
-        H5FD_s3comms_s3r_open(url_shakespeare, (const char *)s3_test_aws_region,
-                              (const char *)s3_test_aws_access_key_id, (const unsigned char *)EMPTY_SHA256);
+    handle = H5FD_s3comms_s3r_open(
+        url_shakespeare, (const char *)s3_test_aws_region, (const char *)s3_test_aws_access_key_id,
+        (const unsigned char *)EMPTY_SHA256, (const char *)s3_test_aws_security_token);
     FAIL_IF(handle != NULL);
 
     /*******************************
@@ -1881,7 +1880,7 @@ test_s3r_open(void)
 
     /* anonymous
      */
-    handle = H5FD_s3comms_s3r_open(url_raven, NULL, NULL, NULL);
+    handle = H5FD_s3comms_s3r_open(url_raven, NULL, NULL, NULL, NULL);
     FAIL_IF(handle == NULL);
     JSVERIFY(6464, H5FD_s3comms_s3r_get_filesize(handle), "did not get expected filesize")
     JSVERIFY(SUCCEED, H5FD_s3comms_s3r_close(handle), "unable to close file")
@@ -1889,9 +1888,9 @@ test_s3r_open(void)
 
     /* using authentication on anonymously-accessible file?
      */
-    handle =
-        H5FD_s3comms_s3r_open(url_raven, (const char *)s3_test_aws_region,
-                              (const char *)s3_test_aws_access_key_id, (const unsigned char *)signing_key);
+    handle = H5FD_s3comms_s3r_open(
+        url_raven, (const char *)s3_test_aws_region, (const char *)s3_test_aws_access_key_id,
+        (const unsigned char *)signing_key, (const char *)s3_test_aws_security_token);
     FAIL_IF(handle == NULL);
     JSVERIFY(6464, H5FD_s3comms_s3r_get_filesize(handle), NULL)
     JSVERIFY(SUCCEED, H5FD_s3comms_s3r_close(handle), "unable to close file")
@@ -1899,9 +1898,9 @@ test_s3r_open(void)
 
     /* authenticating
      */
-    handle =
-        H5FD_s3comms_s3r_open(url_shakespeare, (const char *)s3_test_aws_region,
-                              (const char *)s3_test_aws_access_key_id, (const unsigned char *)signing_key);
+    handle = H5FD_s3comms_s3r_open(
+        url_shakespeare, (const char *)s3_test_aws_region, (const char *)s3_test_aws_access_key_id,
+        (const unsigned char *)signing_key, (const char *)s3_test_aws_security_token);
     FAIL_IF(handle == NULL);
     JSVERIFY(5458199, H5FD_s3comms_s3r_get_filesize(handle), NULL)
     JSVERIFY(SUCCEED, H5FD_s3comms_s3r_close(handle), "unable to close file")
@@ -1987,7 +1986,7 @@ test_s3r_read(void)
 
     /* open file
      */
-    handle = H5FD_s3comms_s3r_open(url_raven, NULL, NULL, NULL);
+    handle = H5FD_s3comms_s3r_open(url_raven, NULL, NULL, NULL, NULL);
     FAIL_IF(handle == NULL)
     JSVERIFY(6464, H5FD_s3comms_s3r_get_filesize(handle), NULL)