diff --git a/Cargo.toml b/Cargo.toml
index acfbcef5f8..db55fe8c64 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -68,7 +68,7 @@ kamadak-exif = "0.5.5"
 default = ["rayon", "default-formats"]
 
 # Format features
-default-formats = ["avif", "bmp", "dds", "exr", "ff", "gif", "hdr", "ico", "jpeg", "png", "pnm", "qoi", "tga", "tiff", "webp"]
+default-formats = ["avif", "bmp", "dds", "exr", "ff", "gif", "hdr", "ico", "jpeg", "png", "pnm", "qoi", "tga", "tiff", "webp", "xbm"]
 avif = ["dep:ravif", "dep:rgb"]
 bmp = []
 dds = []
@@ -84,6 +84,7 @@ qoi = ["dep:qoi"]
 tga = []
 tiff = ["dep:tiff"]
 webp = ["dep:image-webp"]
+xbm = []
 
 # Other features
 rayon = ["dep:rayon"] # Enables multi-threading
diff --git a/README.md b/README.md
index e3eb168058..c156c30678 100644
--- a/README.md
+++ b/README.md
@@ -59,6 +59,7 @@ image format encoders and decoders.
 | TGA      | Yes                                       | Yes                                     |
 | TIFF     | Yes                                       | Yes                                     |
 | WebP     | Yes                                       | Yes (lossless only)                     |
+| XBM      | ---                                       | Yes                                     |
 
 - \* Requires the `avif-native` feature, uses the libdav1d C library.
 
diff --git a/src/codecs/xbm.rs b/src/codecs/xbm.rs
new file mode 100644
index 0000000000..6624203763
--- /dev/null
+++ b/src/codecs/xbm.rs
@@ -0,0 +1,244 @@
+//! Encoding of XBM images
+//!
+//! # Related Links
+//!
+//! - <https://www.x.org/releases/X11R7.7/doc/libX11/libX11/libX11.html#Manipulating_Bitmaps>
+
+use std::io::Write;
+
+use crate::{
+    color::ExtendedColorType,
+    error::{ImageError, ImageResult, UnsupportedError, UnsupportedErrorKind},
+    image::{ImageEncoder, ImageFormat},
+};
+
+/// XBM encoder
+pub struct XbmEncoder<W: Write> {
+    writer: W,
+}
+
+impl<W: Write> XbmEncoder<W> {
+    /// Creates a new encoder that writes its output to ```writer```.
+    pub fn new(writer: W) -> XbmEncoder<W> {
+        Self { writer }
+    }
+
+    /// Encodes the image `buf` that has dimensions `width` and `height`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `width * height != buf.len()` or `buf` contains pixels other
+    /// than `0` or `1`.
+    #[track_caller]
+    pub fn encode(mut self, name: &str, buf: &[u8], width: u32, height: u32) -> ImageResult<()> {
+        let expected_buffer_len = u64::from(width) * u64::from(height);
+        assert_eq!(
+            expected_buffer_len,
+            buf.len() as u64,
+            "Invalid buffer length: expected {expected_buffer_len} got {} for {width}x{height} image",
+            buf.len(),
+        );
+        assert!(
+            !buf.iter().any(|&p| p > 1),
+            "image contained pixels other than `0` or `1`"
+        );
+        self.writer
+            .write_all(format!("#define {name}_width {width}\n").as_bytes())?;
+        self.writer
+            .write_all(format!("#define {name}_height {height}\n").as_bytes())?;
+        self.writer
+            .write_all(format!("static unsigned char {name}_bits[] = {{\n").as_bytes())?;
+        let mut pixels = Vec::with_capacity(12);
+        for bits_per_line in buf.chunks(width as usize) {
+            for bits in bits_per_line.chunks(8) {
+                let mut byte = 0;
+                for (i, bit) in bits.iter().enumerate() {
+                    byte |= bit << (7 - i);
+                }
+                byte = byte.reverse_bits();
+                pixels.push(byte);
+                // line_width <= 80
+                if pixels.len() == 12 {
+                    let line = pixels
+                        .iter()
+                        .map(|p| format!("{p:#04x}"))
+                        .collect::<Vec<_>>()
+                        .join(", ");
+                    self.writer.write_all(format!("    {line},\n").as_bytes())?;
+                    pixels.clear();
+                }
+            }
+        }
+        if !pixels.is_empty() {
+            let line = pixels
+                .iter()
+                .map(|p| format!("{p:#04x}"))
+                .collect::<Vec<_>>()
+                .join(", ");
+            self.writer.write_all(format!("    {line},\n").as_bytes())?;
+        }
+        self.writer.write_all(b"};\n")?;
+        Ok(())
+    }
+}
+
+impl<W: Write> ImageEncoder for XbmEncoder<W> {
+    #[track_caller]
+    fn write_image(
+        self,
+        buf: &[u8],
+        width: u32,
+        height: u32,
+        color_type: ExtendedColorType,
+    ) -> ImageResult<()> {
+        if color_type != ExtendedColorType::L1 {
+            return Err(ImageError::Unsupported(
+                UnsupportedError::from_format_and_kind(
+                    ImageFormat::Xbm.into(),
+                    UnsupportedErrorKind::Color(color_type),
+                ),
+            ));
+        }
+        self.encode("image", buf, width, height)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::str;
+
+    use super::*;
+
+    #[test]
+    fn write() {
+        let mut writer = [0; 132];
+        // "R" (8x7)
+        let buf = b"\x00\x00\x00\x00\x00\x00\x00\x00\
+\x00\x00\x01\x01\x01\x00\x00\x00\
+\x00\x00\x01\x00\x00\x01\x00\x00\
+\x00\x00\x01\x01\x01\x00\x00\x00\
+\x00\x00\x01\x00\x00\x01\x00\x00\
+\x00\x00\x01\x01\x01\x00\x00\x00\
+\x00\x00\x00\x00\x00\x00\x00\x00";
+        let expected = "#define image_width 8
+#define image_height 7
+static unsigned char image_bits[] = {
+    0x00, 0x1c, 0x24, 0x1c, 0x24, 0x1c, 0x00,
+};
+";
+        XbmEncoder::new(&mut writer[..])
+            .write_image(buf, 8, 7, ExtendedColorType::L1)
+            .unwrap();
+        assert_eq!(str::from_utf8(&writer).unwrap(), expected);
+    }
+
+    #[test]
+    fn write_16x14() {
+        let mut writer = [0; 268];
+        // "R" (16x14)
+        let buf = b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x01\x01\x01\x01\x01\x01\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x01\x01\x01\x01\x01\x01\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\
+\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\
+\x00\x00\x00\x00\x01\x01\x01\x01\x01\x01\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x01\x01\x01\x01\x01\x01\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\
+\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\
+\x00\x00\x00\x00\x01\x01\x01\x01\x01\x01\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x01\x01\x01\x01\x01\x01\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";
+        let expected = "#define image_width 16
+#define image_height 14
+static unsigned char image_bits[] = {
+    0x00, 0x00, 0x00, 0x00, 0xf0, 0x03, 0xf0, 0x03, 0x30, 0x0c, 0x30, 0x0c,
+    0xf0, 0x03, 0xf0, 0x03, 0x30, 0x0c, 0x30, 0x0c, 0xf0, 0x03, 0xf0, 0x03,
+    0x00, 0x00, 0x00, 0x00,
+};
+";
+        XbmEncoder::new(&mut writer[..])
+            .write_image(buf, 16, 14, ExtendedColorType::L1)
+            .unwrap();
+        assert_eq!(str::from_utf8(&writer).unwrap(), expected);
+    }
+
+    #[test]
+    fn write_width_7() {
+        let mut writer = [0; 126];
+        // "I" (7x6)
+        let buf = b"\x00\x00\x00\x00\x00\x00\x00\
+\x00\x00\x01\x01\x01\x00\x00\
+\x00\x00\x00\x01\x00\x00\x00\
+\x00\x00\x00\x01\x00\x00\x00\
+\x00\x00\x01\x01\x01\x00\x00\
+\x00\x00\x00\x00\x00\x00\x00";
+        let expected = "#define image_width 7
+#define image_height 6
+static unsigned char image_bits[] = {
+    0x00, 0x1c, 0x08, 0x08, 0x1c, 0x00,
+};
+";
+        XbmEncoder::new(&mut writer[..])
+            .write_image(buf, 7, 6, ExtendedColorType::L1)
+            .unwrap();
+        assert_eq!(str::from_utf8(&writer).unwrap(), expected);
+    }
+
+    #[test]
+    fn write_width_14() {
+        let mut writer = [0; 240];
+        // "I" (14x12)
+        let buf = b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x01\x01\x01\x01\x01\x01\x00\x00\x00\x00\
+\x00\x00\x00\x00\x01\x01\x01\x01\x01\x01\x00\x00\x00\x00\
+\x00\x00\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x00\x00\x01\x01\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x01\x01\x01\x01\x01\x01\x00\x00\x00\x00\
+\x00\x00\x00\x00\x01\x01\x01\x01\x01\x01\x00\x00\x00\x00\
+\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
+\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";
+        let expected = "#define image_width 14
+#define image_height 12
+static unsigned char image_bits[] = {
+    0x00, 0x00, 0x00, 0x00, 0xf0, 0x03, 0xf0, 0x03, 0xc0, 0x00, 0xc0, 0x00,
+    0xc0, 0x00, 0xc0, 0x00, 0xf0, 0x03, 0xf0, 0x03, 0x00, 0x00, 0x00, 0x00,
+};
+";
+        XbmEncoder::new(&mut writer[..])
+            .write_image(buf, 14, 12, ExtendedColorType::L1)
+            .unwrap();
+        assert_eq!(str::from_utf8(&writer).unwrap(), expected);
+    }
+
+    #[test]
+    fn write_invalid_extended_color_type() {
+        let mut writer = [];
+        let buf = [0; 8];
+        assert!(XbmEncoder::new(&mut writer[..])
+            .write_image(&buf, 8, 1, ExtendedColorType::Rgba8)
+            .is_err());
+    }
+
+    #[test]
+    #[should_panic(expected = "Invalid buffer length: expected 32 got 8 for 16x2 image")]
+    fn write_invalid_dimensions() {
+        let mut writer = [];
+        let buf = [0; 8];
+        let _: ImageResult<()> =
+            XbmEncoder::new(&mut writer[..]).write_image(&buf, 16, 2, ExtendedColorType::L1);
+    }
+
+    #[test]
+    #[should_panic(expected = "image contained pixels other than `0` or `1`")]
+    fn write_invalid_pixels() {
+        let mut writer = [];
+        let buf = b"\x00\x01\x02\x03\x03\x02\x01\x00";
+        let _: ImageResult<()> =
+            XbmEncoder::new(&mut writer[..]).write_image(buf, 8, 1, ExtendedColorType::L1);
+    }
+}
diff --git a/src/image.rs b/src/image.rs
index 74822d4173..a707db604c 100644
--- a/src/image.rs
+++ b/src/image.rs
@@ -65,6 +65,9 @@ pub enum ImageFormat {
 
     /// An Image in QOI Format
     Qoi,
+
+    /// An Image in XBM Format
+    Xbm,
 }
 
 impl ImageFormat {
@@ -103,6 +106,7 @@ impl ImageFormat {
                 "pbm" | "pam" | "ppm" | "pgm" => ImageFormat::Pnm,
                 "ff" => ImageFormat::Farbfeld,
                 "qoi" => ImageFormat::Qoi,
+                "xbm" => ImageFormat::Xbm,
                 _ => return None,
             })
         }
@@ -178,6 +182,7 @@ impl ImageFormat {
             // Qoi's MIME type is being worked on.
             // See: https://github.com/phoboslab/qoi/issues/167
             "image/x-qoi" => Some(ImageFormat::Qoi),
+            "image/x-xbitmap" => Some(ImageFormat::Xbm),
             _ => None,
         }
     }
@@ -225,6 +230,7 @@ impl ImageFormat {
             ImageFormat::Qoi => "image/x-qoi",
             // farbfeld's MIME type taken from https://www.wikidata.org/wiki/Q28206109
             ImageFormat::Farbfeld => "application/octet-stream",
+            ImageFormat::Xbm => "image/x-xbitmap",
         }
     }
 
@@ -249,6 +255,7 @@ impl ImageFormat {
             ImageFormat::Farbfeld => true,
             ImageFormat::Avif => true,
             ImageFormat::Qoi => true,
+            ImageFormat::Xbm => false,
         }
     }
 
@@ -273,6 +280,7 @@ impl ImageFormat {
             ImageFormat::OpenExr => true,
             ImageFormat::Dds => false,
             ImageFormat::Qoi => true,
+            ImageFormat::Xbm => true,
         }
     }
 
@@ -304,6 +312,7 @@ impl ImageFormat {
             // According to: https://aomediacodec.github.io/av1-avif/#mime-registration
             ImageFormat::Avif => &["avif"],
             ImageFormat::Qoi => &["qoi"],
+            ImageFormat::Xbm => &["xbm"],
         }
     }
 
@@ -326,6 +335,7 @@ impl ImageFormat {
             ImageFormat::Farbfeld => cfg!(feature = "ff"),
             ImageFormat::Avif => cfg!(feature = "avif"),
             ImageFormat::Qoi => cfg!(feature = "qoi"),
+            ImageFormat::Xbm => false,
             ImageFormat::Dds => false,
         }
     }
@@ -349,6 +359,7 @@ impl ImageFormat {
             ImageFormat::OpenExr => cfg!(feature = "exr"),
             ImageFormat::Qoi => cfg!(feature = "qoi"),
             ImageFormat::Hdr => cfg!(feature = "hdr"),
+            ImageFormat::Xbm => cfg!(feature = "xbm"),
             ImageFormat::Dds => false,
         }
     }
@@ -371,6 +382,7 @@ impl ImageFormat {
             ImageFormat::Qoi,
             ImageFormat::Dds,
             ImageFormat::Hdr,
+            ImageFormat::Xbm,
         ]
         .iter()
         .copied()
diff --git a/src/image_reader/free_functions.rs b/src/image_reader/free_functions.rs
index 7a9bb34400..e72c009e5e 100644
--- a/src/image_reader/free_functions.rs
+++ b/src/image_reader/free_functions.rs
@@ -115,6 +115,10 @@ pub(crate) fn write_buffer_impl<W: std::io::Write + Seek>(
         ImageFormat::Hdr => {
             hdr::HdrEncoder::new(buffered_write).write_image(buf, width, height, color)
         }
+        #[cfg(feature = "xbm")]
+        ImageFormat::Xbm => {
+            xbm::XbmEncoder::new(buffered_write).write_image(buf, width, height, color)
+        }
         _ => Err(ImageError::Unsupported(
             UnsupportedError::from_format_and_kind(
                 ImageFormatHint::Unknown,
diff --git a/src/lib.rs b/src/lib.rs
index e34d754709..6b4f4c37c0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -221,6 +221,7 @@ pub mod flat;
 /// | TGA      | Yes                                       | Yes                                     |
 /// | TIFF     | Yes                                       | Yes                                     |
 /// | WebP     | Yes                                       | Yes (lossless only)                     |
+/// | XBM      | ---                                       | Yes                                     |
 ///
 /// - \* Requires the `avif-native` feature, uses the libdav1d C library.
 ///
@@ -276,6 +277,8 @@ pub mod codecs {
     pub mod tiff;
     #[cfg(feature = "webp")]
     pub mod webp;
+    #[cfg(feature = "xbm")]
+    pub mod xbm;
 
     #[cfg(feature = "dds")]
     mod dxt;