diff --git a/spring-data-mongodb/src/main/kotlin/org/springframework/data/mongodb/core/ExecutableMapReduceOperationExtensions.kt b/spring-data-mongodb/src/main/kotlin/org/springframework/data/mongodb/core/ExecutableMapReduceOperationExtensions.kt
new file mode 100644
index 000000000..9e5b4706c
--- /dev/null
+++ b/spring-data-mongodb/src/main/kotlin/org/springframework/data/mongodb/core/ExecutableMapReduceOperationExtensions.kt
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core
+
+import kotlin.reflect.KClass
+
+/**
+ * Extension for [ExecutableMapReduceOperation.mapReduce] providing a [KClass] based variant.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+fun <T : Any> ExecutableMapReduceOperation.mapReduce(entityClass: KClass<T>): ExecutableMapReduceOperation.MapReduceWithMapFunction<T> =
+		mapReduce(entityClass.java)
+
+/**
+ * Extension for [ExecutableMapReduceOperation.mapReduce] leveraging reified type parameters.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+inline fun <reified T : Any> ExecutableMapReduceOperation.mapReduce(): ExecutableMapReduceOperation.MapReduceWithMapFunction<T> =
+		mapReduce(T::class.java)
+
+/**
+ * Extension for [ExecutableMapReduceOperation.MapReduceWithProjection.as] providing a [KClass] based variant.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+fun <T : Any> ExecutableMapReduceOperation.MapReduceWithProjection<T>.asType(resultType: KClass<T>): ExecutableMapReduceOperation.MapReduceWithQuery<T> =
+		`as`(resultType.java)
+
+/**
+ * Extension for [ExecutableMapReduceOperation.MapReduceWithProjection.as] leveraging reified type parameters.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+inline fun <reified T : Any> ExecutableMapReduceOperation.MapReduceWithProjection<T>.asType(): ExecutableMapReduceOperation.MapReduceWithQuery<T> =
+		`as`(T::class.java)
diff --git a/spring-data-mongodb/src/main/kotlin/org/springframework/data/mongodb/core/ReactiveMapReduceOperationExtensions.kt b/spring-data-mongodb/src/main/kotlin/org/springframework/data/mongodb/core/ReactiveMapReduceOperationExtensions.kt
new file mode 100644
index 000000000..6524ef266
--- /dev/null
+++ b/spring-data-mongodb/src/main/kotlin/org/springframework/data/mongodb/core/ReactiveMapReduceOperationExtensions.kt
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core
+
+import kotlin.reflect.KClass
+
+/**
+ * Extension for [ReactiveMapReduceOperation.mapReduce] providing a [KClass] based variant.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+fun <T : Any> ReactiveMapReduceOperation.mapReduce(entityClass: KClass<T>): ReactiveMapReduceOperation.MapReduceWithMapFunction<T> =
+		mapReduce(entityClass.java)
+
+/**
+ * Extension for [ReactiveMapReduceOperation.mapReduce] leveraging reified type parameters.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+inline fun <reified T : Any> ReactiveMapReduceOperation.mapReduce(): ReactiveMapReduceOperation.MapReduceWithMapFunction<T> =
+		mapReduce(T::class.java)
+
+/**
+ * Extension for [ReactiveMapReduceOperation.MapReduceWithProjection.as] providing a [KClass] based variant.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+fun <T : Any> ReactiveMapReduceOperation.MapReduceWithProjection<T>.asType(resultType: KClass<T>): ReactiveMapReduceOperation.MapReduceWithQuery<T> =
+		`as`(resultType.java)
+
+/**
+ * Extension for [ReactiveMapReduceOperation.MapReduceWithProjection.as] leveraging reified type parameters.
+ *
+ * @author Christoph Strobl
+ * @since 2.1
+ */
+inline fun <reified T : Any> ReactiveMapReduceOperation.MapReduceWithProjection<T>.asType(): ReactiveMapReduceOperation.MapReduceWithQuery<T> =
+		`as`(T::class.java)
diff --git a/spring-data-mongodb/src/test/kotlin/org/springframework/data/mongodb/core/ExecutableMapReduceOperationExtensionsTests.kt b/spring-data-mongodb/src/test/kotlin/org/springframework/data/mongodb/core/ExecutableMapReduceOperationExtensionsTests.kt
new file mode 100644
index 000000000..8b97e1007
--- /dev/null
+++ b/spring-data-mongodb/src/test/kotlin/org/springframework/data/mongodb/core/ExecutableMapReduceOperationExtensionsTests.kt
@@ -0,0 +1,66 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.core
+
+import com.nhaarman.mockito_kotlin.verify
+import example.first.First
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.Answers
+import org.mockito.Mock
+import org.mockito.junit.MockitoJUnitRunner
+
+/**
+ * @author Christoph Strobl
+ */
+@RunWith(MockitoJUnitRunner::class)
+class ExecutableMapReduceOperationExtensionsTests {
+
+	@Mock(answer = Answers.RETURNS_MOCKS)
+	lateinit var operation: ExecutableMapReduceOperation
+
+	@Mock(answer = Answers.RETURNS_MOCKS)
+	lateinit var operationWithProjection: ExecutableMapReduceOperation.MapReduceWithProjection<First>
+
+
+	@Test // DATAMONGO-1929
+	fun `ExecutableMapReduceOperation#mapReduce(KClass) extension should call its Java counterpart`() {
+
+		operation.mapReduce(First::class)
+		verify(operation).mapReduce(First::class.java)
+	}
+
+	@Test // DATAMONGO-1929
+	fun `ExecutableMapReduceOperation#mapReduce() with reified type parameter extension should call its Java counterpart`() {
+
+		operation.mapReduce<First>()
+		verify(operation).mapReduce(First::class.java)
+	}
+
+	@Test // DATAMONGO-1929
+	fun `ExecutableMapReduceOperation#MapReduceWithProjection#asType(KClass) extension should call its Java counterpart`() {
+
+		operationWithProjection.asType(First::class)
+		verify(operationWithProjection).`as`(First::class.java)
+	}
+
+	@Test // DATAMONGO-1929
+	fun `ExecutableMapReduceOperation#MapReduceWithProjection#asType() with reified type parameter extension should call its Java counterpart`() {
+
+		operationWithProjection.asType()
+		verify(operationWithProjection).`as`(First::class.java)
+	}
+}
diff --git a/spring-data-mongodb/src/test/kotlin/org/springframework/data/mongodb/core/ReactiveMapReduceOperationExtensionsTests.kt b/spring-data-mongodb/src/test/kotlin/org/springframework/data/mongodb/core/ReactiveMapReduceOperationExtensionsTests.kt
new file mode 100644
index 000000000..c057b3034
--- /dev/null
+++ b/spring-data-mongodb/src/test/kotlin/org/springframework/data/mongodb/core/ReactiveMapReduceOperationExtensionsTests.kt
@@ -0,0 +1,66 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.data.mongodb.core
+
+import com.nhaarman.mockito_kotlin.verify
+import example.first.First
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.Answers
+import org.mockito.Mock
+import org.mockito.junit.MockitoJUnitRunner
+
+/**
+ * @author Christoph Strobl
+ */
+@RunWith(MockitoJUnitRunner::class)
+class ReactiveMapReduceOperationExtensionsTests {
+
+	@Mock(answer = Answers.RETURNS_MOCKS)
+	lateinit var operation: ReactiveMapReduceOperation
+
+	@Mock(answer = Answers.RETURNS_MOCKS)
+	lateinit var operationWithProjection: ReactiveMapReduceOperation.MapReduceWithProjection<First>
+
+	@Test // DATAMONGO-1929
+	fun `ReactiveMapReduceOperation#mapReduce(KClass) extension should call its Java counterpart`() {
+
+		operation.mapReduce(First::class)
+		verify(operation).mapReduce(First::class.java)
+	}
+
+	@Test // DATAMONGO-1929
+	fun `ReactiveMapReduceOperation#mapReduce() with reified type parameter extension should call its Java counterpart`() {
+
+		operation.mapReduce<First>()
+		verify(operation).mapReduce(First::class.java)
+	}
+
+	@Test // DATAMONGO-1929
+	fun `ReactiveMapReduceOperation#MapReduceWithProjection#asType(KClass) extension should call its Java counterpart`() {
+
+		operationWithProjection.asType(First::class)
+		verify(operationWithProjection).`as`(First::class.java)
+	}
+
+	@Test // DATAMONGO-1929
+	fun `ReactiveMapReduceOperation#MapReduceWithProjection#asType() with reified type parameter extension should call its Java counterpart`() {
+
+		operationWithProjection.asType()
+		verify(operationWithProjection).`as`(First::class.java)
+	}
+}