diff --git a/src/XML/fed/AbstractAttributeExtensibleURIType.php b/src/XML/fed/AbstractAttributeExtensibleURIType.php
new file mode 100644
index 00000000..f06e6f58
--- /dev/null
+++ b/src/XML/fed/AbstractAttributeExtensibleURIType.php
@@ -0,0 +1,87 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\WSSecurity\XML\fed;
+
+use DOMElement;
+use SimpleSAML\Assert\Assert;
+use SimpleSAML\XML\Exception\InvalidDOMElementException;
+use SimpleSAML\XML\ExtendableAttributesTrait;
+use SimpleSAML\XML\StringElementTrait;
+use SimpleSAML\XML\XsNamespace as NS;
+
+/**
+ * An AbstractAttributeExtensibleURIType element
+ *
+ * @package tvdijen/ws-security
+ */
+abstract class AbstractAttributeExtensibleURIType extends AbstractFedElement
+{
+    use ExtendableAttributesTrait;
+    use StringElementTrait;
+
+    /** The namespace-attribute for the xs:anyAttribute element */
+    public const XS_ANY_ATTR_NAMESPACE = NS::OTHER;
+
+
+    /**
+     * @param string $content
+     * @param \SimpleSAML\XML\Attribute[] $namespacedAttributes
+     */
+    public function __construct(string $content, array $namespacedAttributes)
+    {
+        $this->setContent($content);
+        $this->setAttributesNS($namespacedAttributes);
+    }
+
+
+    /**
+     * Validate the content of the element.
+     *
+     * @param string $content  The value to go in the XML textContent
+     * @throws \SimpleSAML\XML\Exception\SchemaViolationException on failure
+     * @return void
+     */
+    protected function validateContent(string $content): void
+    {
+        Assert::validURI($content, SchemaViolationException::class);
+    }
+
+
+    /**
+     * Create a class from XML
+     *
+     * @param \DOMElement $xml
+     * @return static
+     */
+    public static function fromXML(DOMElement $xml): static
+    {
+        Assert::same($xml->localName, static::getLocalName(), InvalidDOMElementException::class);
+        Assert::same($xml->namespaceURI, static::NS, InvalidDOMElementException::class);
+
+        return new static(
+            $xml->textContent,
+            self::getAttributesNSFromXML($xml),
+        );
+    }
+
+
+    /**
+     * Create XML from this class
+     *
+     * @param \DOMElement|null $parent
+     * @return \DOMElement
+     */
+    public function toXML(DOMElement $parent = null): DOMElement
+    {
+        $e = $this->instantiateParentElement($parent);
+        $e->textContent = $this->getContent();
+
+        foreach ($this->getAttributesNS() as $attr) {
+            $attr->toXML($e);
+        }
+
+        return $e;
+    }
+}
diff --git a/src/XML/fed/FederationID.php b/src/XML/fed/FederationID.php
new file mode 100644
index 00000000..7dc129e3
--- /dev/null
+++ b/src/XML/fed/FederationID.php
@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\WSSecurity\XML\fed;
+
+/**
+ * A FederationID element
+ *
+ * @package tvdijen/ws-security
+ */
+final class FederationID extends AbstractAttributeExtensibleURIType
+{
+}
diff --git a/tests/WSSecurity/XML/fed/FederationIDTest.php b/tests/WSSecurity/XML/fed/FederationIDTest.php
new file mode 100644
index 00000000..14291cff
--- /dev/null
+++ b/tests/WSSecurity/XML/fed/FederationIDTest.php
@@ -0,0 +1,62 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\Test\WSSecurity\XML\sp;
+
+use PHPUnit\Framework\TestCase;
+use SimpleSAML\Test\WSSecurity\Constants as C;
+use SimpleSAML\WSSecurity\XML\fed\FederationID;
+use SimpleSAML\XML\Attribute as XMLAttribute;
+use SimpleSAML\XML\DOMDocumentFactory;
+use SimpleSAML\XML\TestUtils\SchemaValidationTestTrait;
+use SimpleSAML\XML\TestUtils\SerializableElementTestTrait;
+
+use function dirname;
+
+/**
+ * Class \SimpleSAML\WSSecurity\XML\fed\FederationIDTest
+ *
+ * @covers \SimpleSAML\WSSecurity\XML\fed\FederationID
+ * @covers \SimpleSAML\WSSecurity\XML\fed\AbstractAttributeExtensibleURIType
+ * @covers \SimpleSAML\WSSecurity\XML\fed\AbstractFedElement
+ *
+ * @package tvdijen/ws-security
+ */
+final class FederationIDTest extends TestCase
+{
+    use SchemaValidationTestTrait;
+    use SerializableElementTestTrait;
+
+
+    /**
+     */
+    public static function setUpBeforeClass(): void
+    {
+        self::$schemaFile = dirname(__FILE__, 5) . '/resources/schemas/ws-federation.xsd';
+
+        self::$testedClass = FederationID::class;
+
+        self::$xmlRepresentation = DOMDocumentFactory::fromFile(
+            dirname(__FILE__, 4) . '/resources/xml/fed_FederationID.xml',
+        );
+    }
+
+
+    // test marshalling
+
+
+    /**
+     * Test creating a FederationID object from scratch.
+     */
+    public function testMarshalling(): void
+    {
+        $attr1 = new XMLAttribute(C::NAMESPACE, 'ssp', 'attr1', 'testval1');
+        $federationID = new FederationID(C::NAMESPACE, [$attr1]);
+
+        $this->assertEquals(
+            self::$xmlRepresentation->saveXML(self::$xmlRepresentation->documentElement),
+            strval($federationID),
+        );
+    }
+}
diff --git a/tests/resources/xml/fed_FederationID.xml b/tests/resources/xml/fed_FederationID.xml
new file mode 100644
index 00000000..be5ef1ff
--- /dev/null
+++ b/tests/resources/xml/fed_FederationID.xml
@@ -0,0 +1 @@
+<fed:FederationID xmlns:fed="http://docs.oasis-open.org/wsfed/federation/200706" xmlns:ssp="urn:x-simplesamlphp:namespace" ssp:attr1="testval1">urn:x-simplesamlphp:namespace</fed:FederationID>