diff --git a/packages/pigeon/CHANGELOG.md b/packages/pigeon/CHANGELOG.md
index 9709fc886d..b4879df952 100644
--- a/packages/pigeon/CHANGELOG.md
+++ b/packages/pigeon/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.1.0-experimental.6
+
+* Added support for void return types.
+
 ## 0.1.0-experimental.5
 
 * Fixed runtime exception in Android with values of ints less than 2^32.
diff --git a/packages/pigeon/lib/dart_generator.dart b/packages/pigeon/lib/dart_generator.dart
index 8544907806..ca223cc5e1 100644
--- a/packages/pigeon/lib/dart_generator.dart
+++ b/packages/pigeon/lib/dart_generator.dart
@@ -23,6 +23,10 @@ void _writeHostApi(Indent indent, Api api) {
         indent.dec();
         indent.dec();
         indent.writeln('');
+        final String returnStatement =
+          func.returnType == 'void'
+          ? '// noop'
+          : 'return ${func.returnType}._fromMap(replyMap[\'${Keys.result}\']);';
         indent.format('''Map replyMap = await channel.send(requestMap);
 if (replyMap['error'] != null) {
 \tMap error = replyMap['${Keys.error}'];
@@ -31,7 +35,7 @@ if (replyMap['error'] != null) {
 \t\t\tmessage: error['${Keys.errorMessage}'],
 \t\t\tdetails: error['${Keys.errorDetails}']);
 } else {
-\treturn ${func.returnType}._fromMap(replyMap[\'${Keys.result}\']);
+\t$returnStatement
 }
 ''');
       });
@@ -67,8 +71,13 @@ void _writeFlutterApi(Indent indent, Api api) {
           final String returnType = func.returnType;
           indent.writeln('Map mapMessage = message as Map;');
           indent.writeln('$argType input = $argType._fromMap(mapMessage);');
-          indent.writeln('$returnType output = api.${func.name}(input);');
-          indent.writeln('return output._toMap();');
+          final String call = 'api.${func.name}(input)';
+          if (returnType == 'void') {
+            indent.writeln('$call;');
+          } else {
+            indent.writeln('$returnType output = $call;');
+            indent.writeln('return output._toMap();');
+          }
         });
       });
     }
diff --git a/packages/pigeon/lib/generator_tools.dart b/packages/pigeon/lib/generator_tools.dart
index 8251cfd665..f064683939 100644
--- a/packages/pigeon/lib/generator_tools.dart
+++ b/packages/pigeon/lib/generator_tools.dart
@@ -4,10 +4,11 @@
 
 import 'dart:convert';
 import 'dart:io';
+import 'dart:mirrors';
 import 'ast.dart';
 
 /// The current version of pigeon.
-const String pigeonVersion = '0.1.0-experimental.5';
+const String pigeonVersion = '0.1.0-experimental.6';
 
 /// Read all the content from [stdin] to a String.
 String readStdin() {
@@ -154,3 +155,8 @@ class Keys {
   /// The key in an error hash for the 'details' value.
   static const String errorDetails = 'details';
 }
+
+/// Returns true if `type` represents 'void'.
+bool isVoid(TypeMirror type) {
+  return MirrorSystem.getName(type.simpleName) == 'void';
+}
diff --git a/packages/pigeon/lib/java_generator.dart b/packages/pigeon/lib/java_generator.dart
index 7850792398..0d227a0c54 100644
--- a/packages/pigeon/lib/java_generator.dart
+++ b/packages/pigeon/lib/java_generator.dart
@@ -66,10 +66,15 @@ void _writeHostApi(Indent indent, Api api) {
                   'HashMap<String, HashMap> wrapped = new HashMap<String, HashMap>();');
               indent.write('try ');
               indent.scoped('{', '}', () {
-                indent
-                    .writeln('$returnType output = api.${method.name}(input);');
-                indent
-                    .writeln('wrapped.put("${Keys.result}", output.toMap());');
+                final String call = 'api.${method.name}(input)';
+                if (method.returnType == 'void') {
+                  indent.writeln('$call;');
+                  indent.writeln('wrapped.put("${Keys.result}", null);');
+                } else {
+                  indent.writeln('$returnType output = $call;');
+                  indent.writeln(
+                      'wrapped.put("${Keys.result}", output.toMap());');
+                }
               });
               indent.write('catch (Exception exception) ');
               indent.scoped('{', '}', () {
@@ -102,8 +107,10 @@ void _writeFlutterApi(Indent indent, Api api) {
     });
     for (Method func in api.methods) {
       final String channelName = makeChannelName(api, func);
+      final String returnType =
+          func.returnType == 'void' ? 'Void' : func.returnType;
       indent.write(
-          'public void ${func.name}(${func.argType} argInput, Reply<${func.returnType}> callback) ');
+          'public void ${func.name}(${func.argType} argInput, Reply<$returnType> callback) ');
       indent.scoped('{', '}', () {
         indent.writeln('BasicMessageChannel<Object> channel =');
         indent.inc();
@@ -118,10 +125,14 @@ void _writeFlutterApi(Indent indent, Api api) {
         indent.scoped('{', '});', () {
           indent.write('public void reply(Object channelReply) ');
           indent.scoped('{', '}', () {
-            indent.writeln('HashMap outputMap = (HashMap)channelReply;');
-            indent.writeln(
-                '${func.returnType} output = ${func.returnType}.fromMap(outputMap);');
-            indent.writeln('callback.reply(output);');
+            if (func.returnType == 'void') {
+              indent.writeln('callback.reply(null);');
+            } else {
+              indent.writeln('HashMap outputMap = (HashMap)channelReply;');
+              indent.writeln(
+                  '${func.returnType} output = ${func.returnType}.fromMap(outputMap);');
+              indent.writeln('callback.reply(output);');
+            }
           });
         });
       });
diff --git a/packages/pigeon/lib/objc_generator.dart b/packages/pigeon/lib/objc_generator.dart
index 26185e4b75..9e38008257 100644
--- a/packages/pigeon/lib/objc_generator.dart
+++ b/packages/pigeon/lib/objc_generator.dart
@@ -26,6 +26,12 @@ String _className(String prefix, String className) {
   }
 }
 
+String _callbackForType(String dartType, String objcType) {
+  return dartType == 'void'
+      ? 'void(^)(NSError*)'
+      : 'void(^)($objcType*, NSError*)';
+}
+
 const Map<String, String> _objcTypeForDartTypeMap = <String, String>{
   'bool': 'NSNumber *',
   'int': 'NSNumber *',
@@ -101,10 +107,13 @@ void generateObjcHeader(ObjcOptions options, Root root, StringSink sink) {
     if (api.location == ApiLocation.host) {
       indent.writeln('@protocol $apiName');
       for (Method func in api.methods) {
-        final String returnType = _className(options.prefix, func.returnType);
+        final String returnTypeName =
+            _className(options.prefix, func.returnType);
         final String argType = _className(options.prefix, func.argType);
+        final String returnType =
+            func.returnType == 'void' ? 'void' : '$returnTypeName *';
         indent.writeln(
-            '-($returnType *)${func.name}:($argType*)input error:(FlutterError **)error;');
+            '-($returnType)${func.name}:($argType*)input error:(FlutterError **)error;');
       }
       indent.writeln('@end');
       indent.writeln('');
@@ -118,8 +127,9 @@ void generateObjcHeader(ObjcOptions options, Root root, StringSink sink) {
       for (Method func in api.methods) {
         final String returnType = _className(options.prefix, func.returnType);
         final String argType = _className(options.prefix, func.argType);
+        final String callbackType = _callbackForType(func.returnType, returnType);
         indent.writeln(
-            '- (void)${func.name}:($argType*)input completion:(void(^)($returnType*, NSError*))completion;');
+            '- (void)${func.name}:($argType*)input completion:($callbackType)completion;');
       }
       indent.writeln('@end');
     }
@@ -176,9 +186,14 @@ void _writeHostApiSource(Indent indent, ObjcOptions options, Api api) {
                 _className(options.prefix, func.returnType);
             indent.writeln('$argType *input = [$argType fromMap:message];');
             indent.writeln('FlutterError *error;');
-            indent.writeln(
-                '$returnType *output = [api ${func.name}:input error:&error];');
-            indent.writeln('callback(wrapResult([output toMap], error));');
+            final String call = '[api ${func.name}:input error:&error]';
+            if (func.returnType == 'void') {
+              indent.writeln('$call;');
+              indent.writeln('callback(wrapResult(nil, error));');
+            } else {
+              indent.writeln('$returnType *output = $call;');
+              indent.writeln('callback(wrapResult([output toMap], error));');
+            }
           });
         });
         indent.write('else ');
@@ -213,8 +228,10 @@ void _writeFlutterApiSource(Indent indent, ObjcOptions options, Api api) {
   for (Method func in api.methods) {
     final String returnType = _className(options.prefix, func.returnType);
     final String argType = _className(options.prefix, func.argType);
+    final String callbackType = _callbackForType(func.returnType, returnType);
+
     indent.write(
-        '- (void)${func.name}:($argType*)input completion:(void(^)($returnType*, NSError*))completion ');
+        '- (void)${func.name}:($argType*)input completion:($callbackType)completion ');
     indent.scoped('{', '}', () {
       indent.writeln('FlutterBasicMessageChannel *channel =');
       indent.inc();
@@ -227,10 +244,14 @@ void _writeFlutterApiSource(Indent indent, ObjcOptions options, Api api) {
       indent.writeln('NSDictionary* inputMap = [input toMap];');
       indent.write('[channel sendMessage:inputMap reply:^(id reply) ');
       indent.scoped('{', '}];', () {
-        indent.writeln('NSDictionary* outputMap = reply;');
-        indent
-            .writeln('$returnType * output = [$returnType fromMap:outputMap];');
-        indent.writeln('completion(output, nil);');
+        if (func.returnType == 'void') {
+          indent.writeln('completion(nil);');
+        } else {
+          indent.writeln('NSDictionary* outputMap = reply;');
+          indent.writeln(
+              '$returnType * output = [$returnType fromMap:outputMap];');
+          indent.writeln('completion(output, nil);');
+        }
       });
     });
   }
diff --git a/packages/pigeon/lib/pigeon_lib.dart b/packages/pigeon/lib/pigeon_lib.dart
index a3e16c81dc..920c2cf22c 100644
--- a/packages/pigeon/lib/pigeon_lib.dart
+++ b/packages/pigeon/lib/pigeon_lib.dart
@@ -11,6 +11,7 @@ import 'package:pigeon/java_generator.dart';
 
 import 'ast.dart';
 import 'dart_generator.dart';
+import 'generator_tools.dart';
 import 'objc_generator.dart';
 
 const List<String> _validTypes = <String>[
@@ -152,7 +153,9 @@ class Pigeon {
     for (ClassMirror apiMirror in apis) {
       for (DeclarationMirror declaration in apiMirror.declarations.values) {
         if (declaration is MethodMirror && !declaration.isConstructor) {
-          classes.add(declaration.returnType);
+          if (!isVoid(declaration.returnType)) {
+            classes.add(declaration.returnType);
+          }
           classes.add(declaration.parameters[0].type);
         }
       }
diff --git a/packages/pigeon/pigeons/voidflutter.dart b/packages/pigeon/pigeons/voidflutter.dart
new file mode 100644
index 0000000000..ec0e93a4ce
--- /dev/null
+++ b/packages/pigeon/pigeons/voidflutter.dart
@@ -0,0 +1,14 @@
+// Copyright 2020 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:pigeon/pigeon_lib.dart';
+
+class SetRequest {
+  int value; 
+}
+
+@FlutterApi()
+abstract class Api {
+  void setValue(SetRequest request);
+}
diff --git a/packages/pigeon/pigeons/voidhost.dart b/packages/pigeon/pigeons/voidhost.dart
new file mode 100644
index 0000000000..b1eb5197c8
--- /dev/null
+++ b/packages/pigeon/pigeons/voidhost.dart
@@ -0,0 +1,14 @@
+// Copyright 2020 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:pigeon/pigeon_lib.dart';
+
+class SetRequest {
+  int value; 
+}
+
+@HostApi()
+abstract class Api {
+  void setValue(SetRequest request);
+}
diff --git a/packages/pigeon/pubspec.yaml b/packages/pigeon/pubspec.yaml
index 1ce025091f..32e001ad4e 100644
--- a/packages/pigeon/pubspec.yaml
+++ b/packages/pigeon/pubspec.yaml
@@ -1,5 +1,5 @@
 name: pigeon
-version: 0.1.0-experimental.5
+version: 0.1.0-experimental.6
 description: Code generator tool to make communication between Flutter and the host platform type-safe and easier.
 homepage: https://github.com/flutter/packages/tree/master/packages/pigeon
 dependencies:
diff --git a/packages/pigeon/test/dart_generator_test.dart b/packages/pigeon/test/dart_generator_test.dart
index 14fbde3e6d..6da6551d81 100644
--- a/packages/pigeon/test/dart_generator_test.dart
+++ b/packages/pigeon/test/dart_generator_test.dart
@@ -81,4 +81,39 @@ void main() {
     expect(code, contains('abstract class Api'));
     expect(code, contains('void ApiSetup(Api'));
   });
+
+  test('host void', () {
+    final Root root = Root(apis: <Api>[
+      Api(name: 'Api', location: ApiLocation.host, methods: <Method>[
+        Method(name: 'doSomething', argType: 'Input', returnType: 'void')
+      ])
+    ], classes: <Class>[
+      Class(
+          name: 'Input',
+          fields: <Field>[Field(name: 'input', dataType: 'String')]),
+    ]);
+    final StringBuffer sink = StringBuffer();
+    generateDart(root, sink);
+    final String code = sink.toString();
+    expect(code, contains('Future<void> doSomething'));
+    expect(code, contains('// noop'));
+  });
+
+  test('flutter void', () {
+    final Root root = Root(apis: <Api>[
+      Api(name: 'Api', location: ApiLocation.flutter, methods: <Method>[
+        Method(name: 'doSomething', argType: 'Input', returnType: 'void')
+      ])
+    ], classes: <Class>[
+      Class(
+          name: 'Input',
+          fields: <Field>[Field(name: 'input', dataType: 'String')]),
+    ]);
+    final StringBuffer sink = StringBuffer();
+    generateDart(root, sink);
+    final String code = sink.toString();
+    expect(code, isNot(matches('=.*doSomething')));
+    expect(code, contains('doSomething('));
+    expect(code, isNot(contains('._toMap()')));
+  });
 }
diff --git a/packages/pigeon/test/java_generator_test.dart b/packages/pigeon/test/java_generator_test.dart
index 6c51a70343..0c2f578869 100644
--- a/packages/pigeon/test/java_generator_test.dart
+++ b/packages/pigeon/test/java_generator_test.dart
@@ -121,4 +121,43 @@ void main() {
     expect(code, contains('public static class Api'));
     expect(code, matches('doSomething.*Input.*Output'));
   });
+
+  test('gen host void api', () {
+    final Root root = Root(apis: <Api>[
+      Api(name: 'Api', location: ApiLocation.host, methods: <Method>[
+        Method(name: 'doSomething', argType: 'Input', returnType: 'void')
+      ])
+    ], classes: <Class>[
+      Class(
+          name: 'Input',
+          fields: <Field>[Field(name: 'input', dataType: 'String')]),
+    ]);
+    final StringBuffer sink = StringBuffer();
+    final JavaOptions javaOptions = JavaOptions();
+    javaOptions.className = 'Messages';
+    generateJava(javaOptions, root, sink);
+    final String code = sink.toString();
+    expect(code, isNot(matches('=.*doSomething')));
+    expect(code, contains('doSomething('));
+  });
+
+  test('gen flutter void api', () {
+    final Root root = Root(apis: <Api>[
+      Api(name: 'Api', location: ApiLocation.flutter, methods: <Method>[
+        Method(name: 'doSomething', argType: 'Input', returnType: 'void')
+      ])
+    ], classes: <Class>[
+      Class(
+          name: 'Input',
+          fields: <Field>[Field(name: 'input', dataType: 'String')]),
+    ]);
+    final StringBuffer sink = StringBuffer();
+    final JavaOptions javaOptions = JavaOptions();
+    javaOptions.className = 'Messages';
+    generateJava(javaOptions, root, sink);
+    final String code = sink.toString();
+    expect(code, contains('Reply<Void>'));
+    expect(code, isNot(contains('.fromMap(')));
+    expect(code, contains('callback.reply(null)'));
+  });
 }
diff --git a/packages/pigeon/test/objc_generator_test.dart b/packages/pigeon/test/objc_generator_test.dart
index e19c3849c3..4cc89302e6 100644
--- a/packages/pigeon/test/objc_generator_test.dart
+++ b/packages/pigeon/test/objc_generator_test.dart
@@ -266,4 +266,71 @@ void main() {
     expect(code, contains('@implementation Api'));
     expect(code, matches('void.*doSomething.*Input.*Output.*{'));
   });
+
+  test('gen host void header', () {
+    final Root root = Root(apis: <Api>[
+      Api(name: 'Api', location: ApiLocation.host, methods: <Method>[
+        Method(name: 'doSomething', argType: 'Input', returnType: 'void')
+      ])
+    ], classes: <Class>[
+      Class(
+          name: 'Input',
+          fields: <Field>[Field(name: 'input', dataType: 'String')]),
+    ]);
+    final StringBuffer sink = StringBuffer();
+    generateObjcHeader(ObjcOptions(header: 'foo.h', prefix: 'ABC'), root, sink);
+    final String code = sink.toString();
+    expect(code, contains('(void)doSomething'));
+  });
+
+  test('gen host void source', () {
+    final Root root = Root(apis: <Api>[
+      Api(name: 'Api', location: ApiLocation.host, methods: <Method>[
+        Method(name: 'doSomething', argType: 'Input', returnType: 'void')
+      ])
+    ], classes: <Class>[
+      Class(
+          name: 'Input',
+          fields: <Field>[Field(name: 'input', dataType: 'String')]),
+    ]);
+    final StringBuffer sink = StringBuffer();
+    generateObjcSource(ObjcOptions(header: 'foo.h', prefix: 'ABC'), root, sink);
+    final String code = sink.toString();
+    expect(code, isNot(matches('=.*doSomething')));
+    expect(code, matches('[.*doSomething:.*]'));
+    expect(code, contains('callback(wrapResult(nil, error))'));
+  });
+
+  test('gen flutter void header', () {
+    final Root root = Root(apis: <Api>[
+      Api(name: 'Api', location: ApiLocation.flutter, methods: <Method>[
+        Method(name: 'doSomething', argType: 'Input', returnType: 'void')
+      ])
+    ], classes: <Class>[
+      Class(
+          name: 'Input',
+          fields: <Field>[Field(name: 'input', dataType: 'String')]),
+    ]);
+    final StringBuffer sink = StringBuffer();
+    generateObjcHeader(ObjcOptions(header: 'foo.h', prefix: 'ABC'), root, sink);
+    final String code = sink.toString();
+    expect(code, contains('completion:(void(^)(NSError*))'));
+  });
+
+  test('gen flutter void source', () {
+    final Root root = Root(apis: <Api>[
+      Api(name: 'Api', location: ApiLocation.flutter, methods: <Method>[
+        Method(name: 'doSomething', argType: 'Input', returnType: 'void')
+      ])
+    ], classes: <Class>[
+      Class(
+          name: 'Input',
+          fields: <Field>[Field(name: 'input', dataType: 'String')]),
+    ]);
+    final StringBuffer sink = StringBuffer();
+    generateObjcSource(ObjcOptions(header: 'foo.h', prefix: 'ABC'), root, sink);
+    final String code = sink.toString();
+    expect(code, contains('completion:(void(^)(NSError*))'));
+    expect(code, contains('completion(nil)'));
+  });
 }
diff --git a/packages/pigeon/test/pigeon_lib_test.dart b/packages/pigeon/test/pigeon_lib_test.dart
index 8b2296f6c6..05ae811a8b 100644
--- a/packages/pigeon/test/pigeon_lib_test.dart
+++ b/packages/pigeon/test/pigeon_lib_test.dart
@@ -38,6 +38,11 @@ abstract class AFlutterApi {
   Output1 doit(Input1 input);
 }
 
+@HostApi()
+abstract class VoidApi {
+  void doit(Input1 input);
+}
+
 void main() {
   test('parse args - input', () {
     final PigeonOptions opts =
@@ -145,4 +150,14 @@ void main() {
     expect(results.root.apis[0].name, equals('AFlutterApi'));
     expect(results.root.apis[0].location, equals(ApiLocation.flutter));
   });
+
+  test('void host api', () {
+    final Pigeon pigeon = Pigeon.setup();
+    final ParseResults results = pigeon.parse(<Type>[VoidApi]);
+    expect(results.errors.length, equals(0));
+    expect(results.root.apis.length, equals(1));
+    expect(results.root.apis[0].methods.length, equals(1));
+    expect(results.root.apis[0].name, equals('VoidApi'));
+    expect(results.root.apis[0].methods[0].returnType, equals('void'));
+  });
 }