diff --git a/base_classes/NXgoniometer.nxdl.xml b/base_classes/NXgoniometer.nxdl.xml
new file mode 100644
index 0000000000..d12d3b2dd9
--- /dev/null
+++ b/base_classes/NXgoniometer.nxdl.xml
@@ -0,0 +1,70 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<?xml-stylesheet type="text/xsl" href="nxdlformat.xsl" ?>
+<!--
+# NeXus - Neutron and X-ray Common Data Format
+# 
+# Copyright (C) 2025 NeXus International Advisory Committee (NIAC)
+# 
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 3 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+# For further information, see http://www.nexusformat.org
+-->
+<definition xmlns="http://definition.nexusformat.org/nxdl/3.1" category="base"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://definition.nexusformat.org/nxdl/3.1 ../nxdl.xsd"
+    name="NXgoniometer" type="group" extends="NXcomponent">
+
+    <doc>
+        Goniometer rotation angles and sample translations used during a
+        measurement. The goniometers used at neutron and x-ray
+        facilities are typically four-circle or six-circle goniometers,
+        or variants of either one. There is no universally recognized
+        naming convention for angles and translations, so the group
+        should contain a :ref:`NXcite` group, which describes how the
+        angles are defined.
+
+        If the goniometer settings are part of a transformation chain,
+        it is possible to record them as NXtransformation groups instead
+        of as fields. It is still recommended that the names of the
+        groups adhere to the convention referenced in the NXcite group.
+    </doc>
+
+    <group name="convention" type="NXcite">
+        <doc>
+            A reference to a publication or online documentation that
+            describe the convention used in this group to define the
+            names of angles and sample translations.
+        </doc>
+    </group>
+    <field name="goniometer">
+        <doc>
+            The common name for the type of goniometer used in these
+            measurements.
+        </doc>
+    </field>
+	<field name="ROTATION_ANGLE" type="NX_FLOAT" units="NX_ANGLE" nameType="any">
+        <doc>
+            One of the goniometer rotation angles defined by the
+            specified convention.
+        </doc>
+    </field>
+    <field name="SAMPLE_TRANSLATION" type="NX_FLOAT" units="NX_LENGTH" nameType="any">
+        <doc>
+            The translation of the sample from the centre of rotation of
+            the goniometer angles along one of the coordinate axes.
+        </doc>
+    </field>
+
+</definition>
diff --git a/base_classes/NXinstrument.nxdl.xml b/base_classes/NXinstrument.nxdl.xml
index 523761ff14..3ecef78044 100644
--- a/base_classes/NXinstrument.nxdl.xml
+++ b/base_classes/NXinstrument.nxdl.xml
@@ -60,6 +60,7 @@
     <group type="NXfermi_chopper" />
     <group type="NXfilter" />
     <group type="NXflipper" />
+    <group type="NXgoniometer" />
     <group type="NXguide" />
     <group type="NXhistory"/>
     <group type="NXinsertion_device" />