diff --git a/src/XML/fed/AbstractPseudonymType.php b/src/XML/fed/AbstractPseudonymType.php
new file mode 100644
index 00000000..75ff7c20
--- /dev/null
+++ b/src/XML/fed/AbstractPseudonymType.php
@@ -0,0 +1,213 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\WSSecurity\XML\fed;
+
+use DateTimeImmutable;
+use DOMElement;
+use SimpleSAML\Assert\Assert;
+use SimpleSAML\WSSecurity\XML\wsu\Expires;
+use SimpleSAML\WSSecurity\Constants as C;
+use SimpleSAML\XML\Exception\MissingElementException;
+use SimpleSAML\XML\Exception\SchemaViolationException;
+use SimpleSAML\XML\ExtendableAttributesTrait;
+use SimpleSAML\XML\ExtendableElementTrait;
+
+/**
+ * A PseudonymType
+ *
+ * @package tvdijen/ws-security
+ */
+abstract class AbstractPseudonymType extends AbstractFedElement
+{
+    use ExtendableAttributesTrait;
+    use ExtendableElementTrait;
+
+    /** The namespace-attribute for the xs:anyAttribute element */
+    public const XS_ANY_ATTR_NAMESPACE = NS::OTHER;
+
+    /** The namespace-attribute for the xs:any element */
+    public const XS_ANY_ELT_NAMESPACE = NS::ANY;
+
+
+    /**
+     * PseudonymType constructor.
+     *
+     * @param \SimpleSAML\WSSecurity\XML\fed\PseudonymBasis $pseudonymBasis
+     * @param \SimpleSAML\WSSecurity\XML\fed\RelativeTo $relativeTo
+     * @param \SimpleSAML\WSSecurity\XML\wsu\Expires|null $expires
+     * @param \SimpleSAML\WSSecurity\XML\fed\SecurityToken[] $securityToken
+     * @param \SimpleSAML\WSSecurity\XML\fed\ProofToken[] $proofToken
+     * @param \SimpleSAML\XML\SerializableElementInterface[] $childeren
+     * @param \SimpleSAML\XML\Attribute[] $namespacedAttributes
+     */
+    final public function __construct(
+        protected PseudonymBasis $pseudonymBasis,
+        protected RelativeTo $relativeTo,
+        protected ?Expires $expires = null,
+        protected array $securityToken = [],
+        protected array $proofToken = [],
+        array $children = [],
+        array $namespacedAttributes = [],
+    ) {
+        Assert::minCount($securityToken, 1, MissingElementException::class);
+        Assert::allIsInstanceOf(
+            $securityToken,
+            SecurityToken::class,
+            SchemaViolationException::class,
+        );
+        Assert::minCount($proofToken, 1, MissingElementException::class);
+        Assert::allIsInstanceOf(
+            $proofToken,
+            ProofToken::class,
+            SchemaViolationException::class,
+        );
+
+        $this->setElements($children);
+        $this->setAttributesNS($namespacedAttributes);
+    }
+
+
+    /**
+     * Collect the value of the pseudonymBasis-property
+     *
+     * @return \SimpleSAML\WSSecurity\XML\fed\PseudonymBasis
+     */
+    public function getPseudonymBasis(): PseudonymBasis
+    {
+        return $this->pseudonymBasis;
+    }
+
+
+    /**
+     * Collect the value of the relativeTo-property
+     *
+     * @return \SimpleSAML\WSSecurity\XML\fed\RelativeTo
+     */
+    public function getRelativeTo(): RelativeTo
+    {
+        return $this->relativeTo;
+    }
+
+
+    /**
+     * Collect the value of the expires-property
+     *
+     * @return \SimpleSAML\WSSecurity\XML\wsu\Expires|null
+     */
+    public function getExpires(): ?Expires
+    {
+        return $this->expires;
+    }
+
+
+    /**
+     * Collect the value of the securityToken-property
+     *
+     * @return \SimpleSAML\WSSecurity\XML\fed\SecurityToken[]
+     */
+    public function getSecurityToken(): array
+    {
+        return $this->securityToken;
+    }
+
+
+    /**
+     * Collect the value of the proofToken-property
+     *
+     * @return \SimpleSAML\WSSecurity\XML\fed\ProofToken[]
+     */
+    public function getProofToken(): array
+    {
+        return $this->proofToken;
+    }
+
+
+    /**
+     * Create an instance of this object from its XML representation.
+     *
+     * @param \DOMElement $xml
+     * @return static
+     *
+     * @throws \SimpleSAML\XML\Exception\InvalidDOMElementException
+     *   if the qualified name of the supplied element is wrong
+     */
+    public static function fromXML(DOMElement $xml): static
+    {
+        Assert::same($xml->localName, static::getLocalName(), InvalidDOMElementException::class);
+        Assert::same($xml->namespaceURI, static::NS, InvalidDOMElementException::class);
+
+        $children = $pseudonymBasis = $relativeTo = $expires = $securityToken = $proofToken = [];
+        foreach ($xml->childNodes as $child) {
+            if (!($child instanceof DOMElement)) {
+                continue;
+            } elseif ($child->namespaceURI === static::NS) {
+                if ($child->localName === 'PseudonymBasis') {
+                    $pseudonymBasis[] = PseudonymBasis::fromXML($child);
+                } elseif ($child->localName === 'RelativeTo') {
+                    $relativeTo[] = RelativeTo::fromXML($child);
+                } elseif ($child->localName === 'SecurityToken') {
+                    $securityToken[] = SecurityToken::fromXML($child);
+                } elseif ($child->localName === 'ProofToken') {
+                    $proofToken[] = ProofToken::fromXML($child);
+                } else {
+                    $children[] = new Chunk($child);
+                }
+                continue;
+            } elseif ($child->namespaceURI === C::NS_SEC_UTIL) {
+                $expires[] = Expires::fromXML($child);
+                continue;
+            }
+
+            $children[] = new Chunk($child);
+        }
+
+        return new static(
+            array_pop($pseudonymBasis),
+            array_pop($relativeTo),
+            array_pop($expires),
+            $securityToken,
+            $proofToken,
+            $children,
+            self::getAttributesNSFromXML($xml),
+        );
+    }
+
+
+    /**
+     * Add this PseudonymType to an XML element.
+     *
+     * @param \DOMElement $parent The element we should append this username token to.
+     * @return \DOMElement
+     */
+    public function toXML(DOMElement $parent = null): DOMElement
+    {
+        $e = parent::instantiateParentElement($parent);
+
+        $this->getPseudonymBasis()->toXML($e);
+        $this->getRelativeTo()->toXML($e);
+        $this->getExpires()?->toXML($e);
+
+        foreach ($this->getSecurityToken() as $st) {
+            $st->toXML($e);
+        }
+
+        foreach ($this->getProofToken() as $pt) {
+            $pt->toXML($e);
+        }
+
+        foreach ($this->getAttributesNS() as $attr) {
+            $attr->toXML($e);
+        }
+
+        /** @psalm-var \SimpleSAML\XML\SerializableElementInterface $child */
+        foreach ($this->getElements() as $child) {
+            if (!$child->isEmptyElement()) {
+                $child->toXML($e);
+            }
+        }
+
+        return $e;
+    }
+}
diff --git a/src/XML/fed/PseudonymType.php b/src/XML/fed/PseudonymType.php
new file mode 100644
index 00000000..342fa26c
--- /dev/null
+++ b/src/XML/fed/PseudonymType.php
@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\WSSecurity\XML\fed;
+
+/**
+ * A PseudonymType element
+ *
+ * @package tvdijen/ws-security
+ */
+final class Pseudonym extends AbstractPseudonymType
+{
+}
diff --git a/tests/resources/xml/fed_Pseudonym.xml b/tests/resources/xml/fed_Pseudonym.xml
new file mode 100644
index 00000000..23cf39db
--- /dev/null
+++ b/tests/resources/xml/fed_Pseudonym.xml
@@ -0,0 +1,16 @@
+<fed:Pseudonym xmlns:fed="http://docs.oasis-open.org/wsfed/federation/200706" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" xmlns:ssp="urn:x-simplesamlphp:namespace" ssp:attr1="testval1">
+  <fed:PseudonymBasis ssp:attr2="testval2">
+    <ssp:Chunk>Basis</ssp:Chunk>
+  </fed:PseudonymBasis>
+  <fed:RelativeTo ssp:attr3="testval3">
+    <ssp:Chunk>Relative</ssp:Chunk>
+  </fed:RelativeTo>
+  <wsu:Expires>2001-10-13T09:00:00Z</wsu:Expires>
+  <fed:SecurityToken ssp:attr4="testval4">
+    <ssp:Chunk>Security</ssp:Chunk>
+  </fed:SecurityToken>
+  <fed:ProofToken ssp:attr5="testval5">
+    <ssp:Chunk>Proof</ssp:Chunk>
+  </fed:ProofToken>
+  <ssp:Chunk>Some</ssp:Chunk>
+</fed:Pseudonym>