diff --git a/quickwit/Cargo.lock b/quickwit/Cargo.lock
index ed1b00fa202..589cbf98bf1 100644
--- a/quickwit/Cargo.lock
+++ b/quickwit/Cargo.lock
@@ -5791,6 +5791,7 @@ dependencies = [
  "anyhow",
  "async-trait",
  "base64 0.21.5",
+ "hex",
  "once_cell",
  "prost",
  "quickwit-actors",
diff --git a/quickwit/quickwit-opentelemetry/Cargo.toml b/quickwit/quickwit-opentelemetry/Cargo.toml
index 84353ebb017..8ed34fcc7c5 100644
--- a/quickwit/quickwit-opentelemetry/Cargo.toml
+++ b/quickwit/quickwit-opentelemetry/Cargo.toml
@@ -13,6 +13,7 @@ documentation = "https://quickwit.io/docs/"
 anyhow = { workspace = true }
 async-trait = { workspace = true }
 base64 = { workspace = true }
+hex = { workspace = true }
 once_cell = { workspace = true }
 prost = { workspace = true }
 serde = { workspace = true }
diff --git a/quickwit/quickwit-opentelemetry/src/otlp/span_id.rs b/quickwit/quickwit-opentelemetry/src/otlp/span_id.rs
index 55f2fb2c21f..0bd8b814552 100644
--- a/quickwit/quickwit-opentelemetry/src/otlp/span_id.rs
+++ b/quickwit/quickwit-opentelemetry/src/otlp/span_id.rs
@@ -17,15 +17,13 @@
 // You should have received a copy of the GNU Affero General Public License
 // along with this program. If not, see <http://www.gnu.org/licenses/>.
 
-use base64::prelude::BASE64_STANDARD;
-use base64::Engine;
 use serde::{de, Deserialize, Deserializer, Serialize, Serializer};
 
 #[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash)]
 pub struct SpanId([u8; 8]);
 
 impl SpanId {
-    pub const BASE64_LENGTH: usize = 12;
+    pub const HEX_LENGTH: usize = 16;
 
     pub fn new(bytes: [u8; 8]) -> Self {
         Self(bytes)
@@ -42,33 +40,29 @@ impl SpanId {
 
 impl Serialize for SpanId {
     fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
-        let b64span_id = BASE64_STANDARD.encode(self.0);
-        serializer.serialize_str(&b64span_id)
+        let hexspan_id = hex::encode(self.0);
+        serializer.serialize_str(&hexspan_id)
     }
 }
 
 impl<'de> Deserialize<'de> for SpanId {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where D: Deserializer<'de> {
-        let b64span_id = String::deserialize(deserializer)?;
+        let hexspan_id = String::deserialize(deserializer)?;
 
-        if b64span_id.len() != SpanId::BASE64_LENGTH {
+        if hexspan_id.len() != SpanId::HEX_LENGTH {
             let message = format!(
-                "base64 span ID must be {} bytes long, got {}",
-                SpanId::BASE64_LENGTH,
-                b64span_id.len()
+                "hex span ID must be {} bytes long, got {}",
+                SpanId::HEX_LENGTH,
+                hexspan_id.len()
             );
             return Err(de::Error::custom(message));
         }
         let mut span_id = [0u8; 8];
-        BASE64_STANDARD
-            // Using the unchecked version here because otherwise the engine gets the wrong size
-            // estimate and fails.
-            .decode_slice_unchecked(b64span_id.as_bytes(), &mut span_id)
-            .map_err(|error| {
-                let message = format!("failed to decode base64 span ID: {:?}", error);
-                de::Error::custom(message)
-            })?;
+        hex::decode_to_slice(hexspan_id, &mut span_id).map_err(|error| {
+            let message = format!("failed to decode hex span ID: {:?}", error);
+            de::Error::custom(message)
+        })?;
         Ok(SpanId(span_id))
     }
 }
@@ -104,7 +98,7 @@ mod tests {
     fn test_span_id_serde() {
         let expected_span_id = SpanId::new([1; 8]);
         let span_id_json = serde_json::to_string(&expected_span_id).unwrap();
-        assert_eq!(span_id_json, r#""AQEBAQEBAQE=""#);
+        assert_eq!(span_id_json, r#""0101010101010101""#);
 
         let span_id = serde_json::from_str::<SpanId>(&span_id_json).unwrap();
         assert_eq!(span_id, expected_span_id,);
diff --git a/quickwit/quickwit-opentelemetry/src/otlp/trace_id.rs b/quickwit/quickwit-opentelemetry/src/otlp/trace_id.rs
index 6e30b64b295..9c14f8904d1 100644
--- a/quickwit/quickwit-opentelemetry/src/otlp/trace_id.rs
+++ b/quickwit/quickwit-opentelemetry/src/otlp/trace_id.rs
@@ -20,14 +20,13 @@
 use base64::display::Base64Display;
 use base64::engine::GeneralPurpose;
 use base64::prelude::BASE64_STANDARD;
-use base64::Engine;
 use serde::{de, Deserialize, Deserializer, Serialize, Serializer};
 
 #[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash)]
 pub struct TraceId([u8; 16]);
 
 impl TraceId {
-    pub const BASE64_LENGTH: usize = 24;
+    pub const HEX_LENGTH: usize = 32;
 
     pub fn new(bytes: [u8; 16]) -> Self {
         Self(bytes)
@@ -49,8 +48,8 @@ impl TraceId {
 impl Serialize for TraceId {
     fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
         if serializer.is_human_readable() {
-            let b64trace_id = BASE64_STANDARD.encode(self.0);
-            serializer.serialize_str(&b64trace_id)
+            let hextrace_id = hex::encode(self.0);
+            serializer.serialize_str(&hextrace_id)
         } else {
             self.0.serialize(serializer)
         }
@@ -61,24 +60,20 @@ impl<'de> Deserialize<'de> for TraceId {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where D: Deserializer<'de> {
         if deserializer.is_human_readable() {
-            let b64trace_id = String::deserialize(deserializer)?;
-            if b64trace_id.len() != TraceId::BASE64_LENGTH {
+            let hextrace_id = String::deserialize(deserializer)?;
+            if hextrace_id.len() != TraceId::HEX_LENGTH {
                 let message = format!(
-                    "base64 trace ID must be {} bytes long, got {}",
-                    TraceId::BASE64_LENGTH,
-                    b64trace_id.len()
+                    "hex trace ID must be {} bytes long, got {}",
+                    TraceId::HEX_LENGTH,
+                    hextrace_id.len()
                 );
                 return Err(de::Error::custom(message));
             }
             let mut trace_id_bytes = [0u8; 16];
-            BASE64_STANDARD
-                // Using the unchecked version here because otherwise the engine gets the wrong size
-                // estimate and fails.
-                .decode_slice_unchecked(b64trace_id.as_bytes(), &mut trace_id_bytes)
-                .map_err(|error| {
-                    let message = format!("failed to decode base64 trace ID: {:?}", error);
-                    de::Error::custom(message)
-                })?;
+            hex::decode_to_slice(hextrace_id, &mut trace_id_bytes).map_err(|error| {
+                let message = format!("failed to decode hex span ID: {:?}", error);
+                de::Error::custom(message)
+            })?;
             Ok(TraceId(trace_id_bytes))
         } else {
             let trace_id_bytes: [u8; 16] = <[u8; 16]>::deserialize(deserializer)?;
@@ -118,7 +113,7 @@ mod tests {
     fn test_trace_id_serde() {
         let expected_trace_id = TraceId::new([1; 16]);
         let trace_id_json = serde_json::to_string(&expected_trace_id).unwrap();
-        assert_eq!(trace_id_json, r#""AQEBAQEBAQEBAQEBAQEBAQ==""#);
+        assert_eq!(trace_id_json, r#""01010101010101010101010101010101""#);
 
         let trace_id = serde_json::from_str::<TraceId>(&trace_id_json).unwrap();
         assert_eq!(trace_id, expected_trace_id,);
diff --git a/quickwit/quickwit-search/src/find_trace_ids_collector.rs b/quickwit/quickwit-search/src/find_trace_ids_collector.rs
index 2b27c9b7381..0f6a8e4fd33 100644
--- a/quickwit/quickwit-search/src/find_trace_ids_collector.rs
+++ b/quickwit/quickwit-search/src/find_trace_ids_collector.rs
@@ -226,7 +226,7 @@ impl SegmentCollector for FindTraceIdsSegmentCollector {
     }
 
     fn harvest(self) -> Self::Fruit {
-        let mut buffer = Vec::with_capacity(TraceId::BASE64_LENGTH);
+        let mut buffer = Vec::with_capacity(TraceId::HEX_LENGTH);
         self.select_trace_ids
             .harvest()
             .into_iter()
diff --git a/quickwit/quickwit-search/src/tests.rs b/quickwit/quickwit-search/src/tests.rs
index ec559d2a4d5..3f282ec674d 100644
--- a/quickwit/quickwit-search/src/tests.rs
+++ b/quickwit/quickwit-search/src/tests.rs
@@ -479,7 +479,7 @@ async fn test_single_node_without_timestamp_with_query_start_timestamp_enabled(
     let start_timestamp = OffsetDateTime::now_utc().unix_timestamp();
     for i in 0..30 {
         let body = format!("info @ t:{}", i + 1);
-        docs.push(json!({"body": body}));
+        docs.push(json!({ "body": body }));
     }
     test_sandbox.add_documents(docs).await?;
 
@@ -1782,6 +1782,8 @@ async fn test_single_node_find_trace_ids_collector() {
               - name: trace_id
                 type: bytes
                 fast: true
+                input_format: hex
+                output_format: hex
               - name: span_timestamp_secs
                 type: datetime
                 fast: true