diff --git a/src/Hydrator/HydratorUtil.php b/src/Hydrator/HydratorUtil.php
index 4046bda..d0e5071 100644
--- a/src/Hydrator/HydratorUtil.php
+++ b/src/Hydrator/HydratorUtil.php
@@ -335,6 +335,43 @@ public static function extractEnums(array $data, array $arrayProperties, array $
         return $data;
     }
 
+    /**
+     * @param array<string, array|object> $data
+     * @param array<string, array<class-string, class-string<HydratorInterface>>> $unions
+     */
+    public static function extractUnions(array $data, array $arrayProperties, array $unions): array
+    {
+        foreach ($unions as $property => $union) {
+            $value = $data[$property];
+            if (in_array($property, $arrayProperties, true)) {
+                assert(is_array($value));
+                $unionValues = [];
+                /** @var object $unionValue */
+                foreach ($value as $unionValue) {
+                    $unionValues[] = self::extractUnion($unionValue, $union);
+                }
+                $data[$property] = $unionValues;
+            } else {
+                assert(is_object($value));
+                $data[$property] = self::extractUnion($value, $union);
+            }
+        }
+
+        return $data;
+    }
+
+    /**
+     * @param array<class-string, class-string<HydratorInterface>> $union
+     */
+    public static function extractUnion(object $object, array $union): bool|array|float|int|string|null
+    {
+        if (! isset($union[$object::class])) {
+            return null;
+        }
+        $extractor = $union[$object::class];
+        return $extractor::extract($object);
+    }
+
     /**
      * @param array<string, class-string<HydratorInterface>> $extractors
      */
diff --git a/test/Hydrator/Asset/ExtractableHydrator.php b/test/Hydrator/Asset/ExtractableHydrator.php
new file mode 100644
index 0000000..5a06b01
--- /dev/null
+++ b/test/Hydrator/Asset/ExtractableHydrator.php
@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+namespace KynxTest\Mezzio\OpenApi\Hydrator\Asset;
+
+use Kynx\Mezzio\OpenApi\Hydrator\HydratorInterface;
+
+use function assert;
+use function is_array;
+
+final class ExtractableHydrator implements HydratorInterface
+{
+    public static function hydrate(mixed $data): object
+    {
+        assert(is_array($data));
+        return new Extractable((string) $data['one'], (int) $data['two'], (bool) $data['three']);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public static function extract(mixed $object): array
+    {
+        assert($object instanceof Extractable);
+        return [
+            'one'   => $object->getOne(),
+            'two'   => $object->getTwo(),
+            'three' => $object->isThree(),
+        ];
+    }
+}
diff --git a/test/Hydrator/Asset/SecondExtractable.php b/test/Hydrator/Asset/SecondExtractable.php
new file mode 100644
index 0000000..7d31666
--- /dev/null
+++ b/test/Hydrator/Asset/SecondExtractable.php
@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace KynxTest\Mezzio\OpenApi\Hydrator\Asset;
+
+final class SecondExtractable
+{
+    public function __construct(private readonly string $value)
+    {
+    }
+
+    public function getValue(): string
+    {
+        return $this->value;
+    }
+}
diff --git a/test/Hydrator/Asset/SecondExtractableHydrator.php b/test/Hydrator/Asset/SecondExtractableHydrator.php
new file mode 100644
index 0000000..5d8e49e
--- /dev/null
+++ b/test/Hydrator/Asset/SecondExtractableHydrator.php
@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+namespace KynxTest\Mezzio\OpenApi\Hydrator\Asset;
+
+use Kynx\Mezzio\OpenApi\Hydrator\HydratorInterface;
+
+use function assert;
+use function is_string;
+
+final class SecondExtractableHydrator implements HydratorInterface
+{
+    public static function hydrate(mixed $data): object
+    {
+        assert(is_string($data));
+        return new SecondExtractable($data);
+    }
+
+    public static function extract(mixed $object): bool|array|float|int|string|null
+    {
+        assert($object instanceof SecondExtractable);
+        return [
+            'value' => $object->getValue(),
+        ];
+    }
+}
diff --git a/test/Hydrator/HydratorUtilTest.php b/test/Hydrator/HydratorUtilTest.php
index a89ad7b..8e11da8 100644
--- a/test/Hydrator/HydratorUtilTest.php
+++ b/test/Hydrator/HydratorUtilTest.php
@@ -11,8 +11,11 @@
 use Kynx\Mezzio\OpenApi\Hydrator\Exception\MissingDiscriminatorException;
 use Kynx\Mezzio\OpenApi\Hydrator\HydratorUtil;
 use KynxTest\Mezzio\OpenApi\Hydrator\Asset\Extractable;
+use KynxTest\Mezzio\OpenApi\Hydrator\Asset\ExtractableHydrator;
 use KynxTest\Mezzio\OpenApi\Hydrator\Asset\GoodHydrator;
 use KynxTest\Mezzio\OpenApi\Hydrator\Asset\MockEnum;
+use KynxTest\Mezzio\OpenApi\Hydrator\Asset\SecondExtractable;
+use KynxTest\Mezzio\OpenApi\Hydrator\Asset\SecondExtractableHydrator;
 use KynxTest\Mezzio\OpenApi\Hydrator\Asset\TypeErrorHydrator;
 use PHPUnit\Framework\TestCase;
 use stdClass;
@@ -494,6 +497,71 @@ public function testExtractEnumsExtrasSingleEnum(): void
         self::assertSame($expected, $actual);
     }
 
+    public function testExtractUnionsExtractsArrayOfUnions(): void
+    {
+        $expected = [
+            'items' => [
+                ['one' => 'a', 'two' => 2, 'three' => true],
+            ],
+        ];
+        $data     = [
+            'items' => [
+                new Extractable('a', 2, true),
+            ],
+        ];
+        $unions   = [
+            'items' => [
+                Extractable::class => ExtractableHydrator::class,
+            ],
+        ];
+
+        $actual = HydratorUtil::extractUnions($data, ['items'], $unions);
+        self::assertSame($expected, $actual);
+    }
+
+    public function testExtractUnionsExtractsSingleUnion(): void
+    {
+        $expected = [
+            'item' => ['one' => 'a', 'two' => 2, 'three' => true],
+        ];
+        $data     = [
+            'item' => new Extractable('a', 2, true),
+        ];
+        $unions   = [
+            'item' => [
+                Extractable::class => ExtractableHydrator::class,
+            ],
+        ];
+
+        $actual = HydratorUtil::extractUnions($data, ['foo'], $unions);
+        self::assertSame($expected, $actual);
+    }
+
+    /**
+     * @dataProvider extractUnionProvider
+     */
+    public function testExtractUnionExtractsCorrectClass(object $extractable, array $expected): void
+    {
+        $union = [
+            Extractable::class       => ExtractableHydrator::class,
+            SecondExtractable::class => SecondExtractableHydrator::class,
+        ];
+
+        $actual = HydratorUtil::extractUnion($extractable, $union);
+        self::assertSame($expected, $actual);
+    }
+
+    /**
+     * @return array<string, array{0: Extractable|SecondExtractable, 1: array}>
+     */
+    public static function extractUnionProvider(): array
+    {
+        return [
+            'first'  => [new Extractable('a', 2, true), ['one' => 'a', 'two' => 2, 'three' => true]],
+            'second' => [new SecondExtractable('foo'), ['value' => 'foo']],
+        ];
+    }
+
     public function testExtractEnumsExtractsArrayOfEnums(): void
     {
         $expected = [