diff --git a/phpdotnet/phd/Package/Generic/XHTML.php b/phpdotnet/phd/Package/Generic/XHTML.php
index 156c5d03..52433334 100644
--- a/phpdotnet/phd/Package/Generic/XHTML.php
+++ b/phpdotnet/phd/Package/Generic/XHTML.php
@@ -392,6 +392,48 @@ abstract class Package_Generic_XHTML extends Format_Abstract_XHTML {
         //phd
         'phd:toc'               => 'format_phd_toc',
 
+        // MathML (namespace http://www.w3.org/1998/Math/MathML)
+        'mml:math'              => 'format_mml_element',
+        // Token
+        'mml:mi'                => 'format_mml_element',
+        'mml:mn'                => 'format_mml_element',
+        'mml:mo'                => 'format_mml_element',
+        'mml:mtext'             => 'format_mml_element',
+        'mml:mspace'            => 'format_mml_element',
+        'mml:ms'                => 'format_mml_element',
+        // Layout
+        'mml:mrow'              => 'format_mml_element',
+        'mml:mfrac'             => 'format_mml_element',
+        'mml:msqrt'             => 'format_mml_element',
+        'mml:mroot'             => 'format_mml_element',
+        'mml:mstyle'            => 'format_mml_element',
+        'mml:merror'            => 'format_mml_element',
+        'mml:mpadded'           => 'format_mml_element',
+        'mml:mphantom'          => 'format_mml_element',
+        'mml:mfenced'           => 'format_mml_element',
+        'mml:menclose'          => 'format_mml_element',
+        // Scripts and limits
+        'mml:msub'              => 'format_mml_element',
+        'mml:msup'              => 'format_mml_element',
+        'mml:msubsup'           => 'format_mml_element',
+        'mml:munder'            => 'format_mml_element',
+        'mml:mover'             => 'format_mml_element',
+        'mml:munderover'        => 'format_mml_element',
+        'mml:mmultiscripts'     => 'format_mml_element',
+        'mml:mprescripts'       => 'format_mml_element',
+        'mml:none'              => 'format_mml_element',
+        // Tables
+        'mml:mtable'            => 'format_mml_element',
+        'mml:mtr'               => 'format_mml_element',
+        'mml:mtd'               => 'format_mml_element',
+        'mml:mlabeledtr'        => 'format_mml_element',
+        // Semantics
+        'mml:semantics'         => 'format_mml_element',
+        'mml:annotation'        => 'format_mml_element',
+        'mml:annotation-xml'    => 'format_mml_element',
+        // Actions
+        'mml:maction'           => 'format_mml_element',
+
     ); /* }}} */
 
     private $mytextmap = array(
@@ -631,6 +673,37 @@ function format_phd_toc($open, $name, $attrs, $props) {
         ) . "</div>\n";
     }
 
+    /**
+    * Handle MathML elements (mml:* namespace).
+    * Strips the "mml:" prefix and outputs the HTML5 local name.
+    */
+    public function format_mml_element($open, $name, $attrs, $props) {
+        $localName = substr($name, 4);
+
+        if ($open) {
+            $attrStr = '';
+
+            // Add xmlns on the <math> root element for XHTML compatibility
+            if ($localName === 'math') {
+                $attrStr .= ' xmlns="' . Reader::XMLNS_MATHML . '"';
+            }
+
+            // Preserve MathML attributes (stored under XMLNS_DOCBOOK as they have no namespace)
+            foreach ($attrs[Reader::XMLNS_DOCBOOK] as $attr => $val) {
+                $attrStr .= ' ' . $attr . '="' . $this->TEXT($val) . '"';
+            }
+
+            // Preserve xml:id as id
+            if (isset($attrs[Reader::XMLNS_XML]["id"])) {
+                $attrStr .= ' id="' . $attrs[Reader::XMLNS_XML]["id"] . '"';
+            }
+
+            return '<' . $localName . $attrStr . ($props["empty"] ? '/>' : '>');
+        }
+
+        return '</' . $localName . '>';
+    }
+
     public function createLink($for, &$desc = null, $type = Format::SDESC) {
         $retval = null;
         if (isset($this->indexes[$for])) {
diff --git a/phpdotnet/phd/Reader.php b/phpdotnet/phd/Reader.php
index 796a2d71..47240f14 100644
--- a/phpdotnet/phd/Reader.php
+++ b/phpdotnet/phd/Reader.php
@@ -7,6 +7,7 @@ class Reader extends \XMLReader
     const XMLNS_XLINK   = "http://www.w3.org/1999/xlink";
     const XMLNS_PHD     = "http://www.php.net/ns/phd";
     const XMLNS_DOCBOOK = "http://docbook.org/ns/docbook";
+    const XMLNS_MATHML  = "http://www.w3.org/1998/Math/MathML";
     
     protected OutputHandler $outputHandler;
 
diff --git a/tests/package/php/data/mathml_rendering.xml b/tests/package/php/data/mathml_rendering.xml
new file mode 100644
index 00000000..c32c7dfe
--- /dev/null
+++ b/tests/package/php/data/mathml_rendering.xml
@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="utf-8"?>
+<chapter xml:id="mathml_rendering" xmlns="http://docbook.org/ns/docbook" xmlns:mml="http://www.w3.org/1998/Math/MathML">
+
+ <section>
+  <para>1. Inline MathML equation</para>
+  <para>
+   The quadratic formula is
+   <mml:math display="inline"><mml:mi>x</mml:mi><mml:mo>=</mml:mo><mml:mfrac><mml:mrow><mml:mo>-</mml:mo><mml:mi>b</mml:mi><mml:mo>±</mml:mo><mml:msqrt><mml:mrow><mml:msup><mml:mi>b</mml:mi><mml:mn>2</mml:mn></mml:msup><mml:mo>-</mml:mo><mml:mn>4</mml:mn><mml:mi>a</mml:mi><mml:mi>c</mml:mi></mml:mrow></mml:msqrt></mml:mrow><mml:mrow><mml:mn>2</mml:mn><mml:mi>a</mml:mi></mml:mrow></mml:mfrac></mml:math>.
+  </para>
+ </section>
+
+ <section>
+  <para>2. Self-closing mspace element</para>
+  <para>
+   <mml:math><mml:mi>a</mml:mi><mml:mspace width="1em"/><mml:mi>b</mml:mi></mml:math>
+  </para>
+ </section>
+
+ <section>
+  <para>3. Element with mathvariant attribute</para>
+  <para>
+   <mml:math><mml:mi mathvariant="bold">x</mml:mi></mml:math>
+  </para>
+ </section>
+
+</chapter>
diff --git a/tests/package/php/mathml_rendering.phpt b/tests/package/php/mathml_rendering.phpt
new file mode 100644
index 00000000..f755da39
--- /dev/null
+++ b/tests/package/php/mathml_rendering.phpt
@@ -0,0 +1,46 @@
+--TEST--
+MathML rendering
+--FILE--
+<?php
+namespace phpdotnet\phd;
+
+require_once __DIR__ . "/../../setup.php";
+
+$xmlFile = __DIR__ . "/data/mathml_rendering.xml";
+
+$config->xmlFile = $xmlFile;
+
+$format = new TestPHPChunkedXHTML($config, $outputHandler);
+
+$render = new TestRender(new Reader($outputHandler), $config, $format);
+
+$render->run();
+?>
+--EXPECT--
+Filename: mathml_rendering.html
+Content:
+<div id="mathml_rendering" class="chapter">
+
+ <div class="section">
+  <p class="para">1. Inline MathML equation</p>
+  <p class="para">
+   The quadratic formula is
+   <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>x</mi><mo>=</mo><mfrac><mrow><mo>-</mo><mi>b</mi><mo>±</mo><msqrt><mrow><msup><mi>b</mi><mn>2</mn></msup><mo>-</mo><mn>4</mn><mi>a</mi><mi>c</mi></mrow></msqrt></mrow><mrow><mn>2</mn><mi>a</mi></mrow></mfrac></math>.
+  </p>
+ </div>
+
+ <div class="section">
+  <p class="para">2. Self-closing mspace element</p>
+  <p class="para">
+   <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>a</mi><mspace width="1em"/><mi>b</mi></math>
+  </p>
+ </div>
+
+ <div class="section">
+  <p class="para">3. Element with mathvariant attribute</p>
+  <p class="para">
+   <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="bold">x</mi></math>
+  </p>
+ </div>
+
+</div>