diff --git a/library/src/main/java/com/pengrad/telegrambot/TelegramBot.java b/library/src/main/java/com/pengrad/telegrambot/TelegramBot.java
index edc2129d..a3afc220 100644
--- a/library/src/main/java/com/pengrad/telegrambot/TelegramBot.java
+++ b/library/src/main/java/com/pengrad/telegrambot/TelegramBot.java
@@ -1,9 +1,14 @@
 package com.pengrad.telegrambot;
 
 import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
 import com.pengrad.telegrambot.impl.FileApi;
 import com.pengrad.telegrambot.impl.TelegramBotClient;
 import com.pengrad.telegrambot.impl.UpdatesHandler;
+import com.pengrad.telegrambot.model.Chat;
 import com.pengrad.telegrambot.model.File;
 import com.pengrad.telegrambot.request.BaseRequest;
 import com.pengrad.telegrambot.request.GetUpdates;
@@ -12,6 +17,8 @@
 import okhttp3.OkHttpClient;
 import okhttp3.logging.HttpLoggingInterceptor;
 
+import java.io.IOException;
+
 /**
  * Stas Parshin
  * 16 October 2015
@@ -115,7 +122,23 @@ private static Interceptor httpLoggingInterceptor() {
         }
 
         private static Gson gson() {
-            return new Gson();
+            final Gson gson = new Gson();
+            TypeAdapter<Chat.Type> chatTypeAdapter = new TypeAdapter<Chat.Type>() {
+                @Override
+                public void write(JsonWriter out, Chat.Type value) throws IOException {
+                    out.value(value == Chat.Type.Private ? "private" : value.name());
+                }
+
+                @Override
+                public Chat.Type read(JsonReader in) throws IOException {
+                    String s = in.nextString();
+                    if (s.equals("private")) return Chat.Type.Private;
+                    else return gson.fromJson(s, Chat.Type.class);
+                }
+            };
+            return new GsonBuilder()
+                    .registerTypeAdapter(Chat.Type.class, chatTypeAdapter)
+                    .create();
         }
 
         private static String apiUrl(String apiUrl, String botToken) {
diff --git a/library/src/main/java/com/pengrad/telegrambot/impl/TelegramBotClient.java b/library/src/main/java/com/pengrad/telegrambot/impl/TelegramBotClient.java
index 59889a40..b361982a 100644
--- a/library/src/main/java/com/pengrad/telegrambot/impl/TelegramBotClient.java
+++ b/library/src/main/java/com/pengrad/telegrambot/impl/TelegramBotClient.java
@@ -91,7 +91,7 @@ private RequestBody createRequestBody(BaseRequest<?, ?> request) {
                 } else if (value instanceof File) {
                     builder.addFormDataPart(name, request.getFileName(), RequestBody.create(contentType, (File) value));
                 } else {
-                    builder.addFormDataPart(name, String.valueOf(value));
+                    builder.addFormDataPart(name, serialize(value));
                 }
             }
 
@@ -99,9 +99,15 @@ private RequestBody createRequestBody(BaseRequest<?, ?> request) {
         } else {
             FormBody.Builder builder = new FormBody.Builder();
             for (Map.Entry<String, Object> parameter : request.getParameters().entrySet()) {
-                builder.add(parameter.getKey(), String.valueOf(parameter.getValue()));
+                builder.add(parameter.getKey(), serialize(parameter.getValue()));
             }
             return builder.build();
         }
     }
+
+    private String serialize(Object value) {
+        return value instanceof String
+                ? String.valueOf(value)
+                : gson.toJson(value);
+    }
 }
diff --git a/library/src/main/java/com/pengrad/telegrambot/model/Chat.java b/library/src/main/java/com/pengrad/telegrambot/model/Chat.java
index a298d567..22f9b4a3 100644
--- a/library/src/main/java/com/pengrad/telegrambot/model/Chat.java
+++ b/library/src/main/java/com/pengrad/telegrambot/model/Chat.java
@@ -1,7 +1,5 @@
 package com.pengrad.telegrambot.model;
 
-import com.google.gson.annotations.SerializedName;
-
 import java.io.Serializable;
 
 /**
@@ -12,7 +10,7 @@ public class Chat implements Serializable {
     private final static long serialVersionUID = 0L;
 
     public enum Type {
-        @SerializedName("private")Private, group, supergroup, channel
+        Private, group, supergroup, channel;
     }
 
     private Long id;
diff --git a/library/src/main/java/com/pengrad/telegrambot/model/MaskPosition.java b/library/src/main/java/com/pengrad/telegrambot/model/MaskPosition.java
index ca47e411..263063bd 100644
--- a/library/src/main/java/com/pengrad/telegrambot/model/MaskPosition.java
+++ b/library/src/main/java/com/pengrad/telegrambot/model/MaskPosition.java
@@ -1,7 +1,5 @@
 package com.pengrad.telegrambot.model;
 
-import com.google.gson.Gson;
-
 import java.io.Serializable;
 
 /**
@@ -10,7 +8,6 @@
  */
 public class MaskPosition implements Serializable {
     private final static long serialVersionUID = 0L;
-    private final static Gson gson = new Gson();
 
     public enum Point {
         forehead, eyes, mouth, chin
diff --git a/library/src/main/java/com/pengrad/telegrambot/model/request/Keyboard.java b/library/src/main/java/com/pengrad/telegrambot/model/request/Keyboard.java
index 4f3c5146..e1afeb7a 100644
--- a/library/src/main/java/com/pengrad/telegrambot/model/request/Keyboard.java
+++ b/library/src/main/java/com/pengrad/telegrambot/model/request/Keyboard.java
@@ -1,7 +1,5 @@
 package com.pengrad.telegrambot.model.request;
 
-import com.google.gson.Gson;
-
 import java.io.Serializable;
 
 /**
@@ -10,13 +8,4 @@
  */
 public abstract class Keyboard implements Serializable {
     private final static long serialVersionUID = 0L;
-
-    // todo remove gson
-    private static Gson gson = new Gson();
-
-    @Override
-    public final String toString() {
-        return gson.toJson(this);
-    }
-
 }
diff --git a/library/src/main/java/com/pengrad/telegrambot/request/AddStickerToSet.java b/library/src/main/java/com/pengrad/telegrambot/request/AddStickerToSet.java
index fafacfae..f55ffb6b 100644
--- a/library/src/main/java/com/pengrad/telegrambot/request/AddStickerToSet.java
+++ b/library/src/main/java/com/pengrad/telegrambot/request/AddStickerToSet.java
@@ -17,6 +17,6 @@ public AddStickerToSet(Integer userId, String name, Object pngSticker, String em
     }
 
     public AddStickerToSet maskPosition(MaskPosition maskPosition) {
-        return add("mask_position", serialize(maskPosition));
+        return add("mask_position", maskPosition);
     }
 }
diff --git a/library/src/main/java/com/pengrad/telegrambot/request/AnswerInlineQuery.java b/library/src/main/java/com/pengrad/telegrambot/request/AnswerInlineQuery.java
index f23a1722..1063ef0e 100644
--- a/library/src/main/java/com/pengrad/telegrambot/request/AnswerInlineQuery.java
+++ b/library/src/main/java/com/pengrad/telegrambot/request/AnswerInlineQuery.java
@@ -11,7 +11,7 @@ public class AnswerInlineQuery extends BaseRequest<AnswerInlineQuery, BaseRespon
 
     public AnswerInlineQuery(String inlineQueryId, InlineQueryResult... results) {
         super(BaseResponse.class);
-        add("inline_query_id", inlineQueryId).add("results", serialize(results));
+        add("inline_query_id", inlineQueryId).add("results", results);
     }
 
     public AnswerInlineQuery cacheTime(int cacheTime) {
diff --git a/library/src/main/java/com/pengrad/telegrambot/request/AnswerShippingQuery.java b/library/src/main/java/com/pengrad/telegrambot/request/AnswerShippingQuery.java
index 5d2c4c59..85986093 100644
--- a/library/src/main/java/com/pengrad/telegrambot/request/AnswerShippingQuery.java
+++ b/library/src/main/java/com/pengrad/telegrambot/request/AnswerShippingQuery.java
@@ -11,7 +11,7 @@ public class AnswerShippingQuery extends BaseRequest<AnswerShippingQuery, BaseRe
 
     public AnswerShippingQuery(String shippingQueryId, ShippingOption... shippingOptions) {
         super(BaseResponse.class);
-        add("shipping_query_id", shippingQueryId).add("ok", true).add("shipping_options", serialize(shippingOptions));
+        add("shipping_query_id", shippingQueryId).add("ok", true).add("shipping_options", shippingOptions);
     }
 
     public AnswerShippingQuery(String shippingQueryId, String errorMessage) {
diff --git a/library/src/main/java/com/pengrad/telegrambot/request/BaseRequest.java b/library/src/main/java/com/pengrad/telegrambot/request/BaseRequest.java
index 0acfcc9d..f1c587db 100644
--- a/library/src/main/java/com/pengrad/telegrambot/request/BaseRequest.java
+++ b/library/src/main/java/com/pengrad/telegrambot/request/BaseRequest.java
@@ -65,15 +65,10 @@ public int getTimeoutSeconds() {
         return 0;
     }
 
+    // todo remove gson dependency
     public String toWebhookResponse() {
         Map<String, Object> fullMap = new HashMap<String, Object>(parameters);
         fullMap.put("method", getMethod());
         return gson.toJson(fullMap);
     }
-
-    // Serialize model objects. Basically convert to json
-    // todo move to TelegramBotClient, let it serialize everything in request time
-    protected String serialize(Object o) {
-        return gson.toJson(o);
-    }
 }
diff --git a/library/src/main/java/com/pengrad/telegrambot/request/CreateNewStickerSet.java b/library/src/main/java/com/pengrad/telegrambot/request/CreateNewStickerSet.java
index b4ff7ac7..86b2e716 100644
--- a/library/src/main/java/com/pengrad/telegrambot/request/CreateNewStickerSet.java
+++ b/library/src/main/java/com/pengrad/telegrambot/request/CreateNewStickerSet.java
@@ -22,6 +22,6 @@ public CreateNewStickerSet containsMasks(boolean containsMasks) {
     }
 
     public CreateNewStickerSet maskPosition(MaskPosition maskPosition) {
-        return add("mask_position", serialize(maskPosition)).containsMasks(true);
+        return add("mask_position", maskPosition).containsMasks(true);
     }
 }
diff --git a/library/src/main/java/com/pengrad/telegrambot/request/GetUpdates.java b/library/src/main/java/com/pengrad/telegrambot/request/GetUpdates.java
index 82c9c7dd..cda20902 100644
--- a/library/src/main/java/com/pengrad/telegrambot/request/GetUpdates.java
+++ b/library/src/main/java/com/pengrad/telegrambot/request/GetUpdates.java
@@ -30,7 +30,7 @@ public GetUpdates timeout(int timeout) {
     }
 
     public GetUpdates allowedUpdates(String... allowedUpdates) {
-        return add("allowed_updates", serialize(allowedUpdates));
+        return add("allowed_updates", allowedUpdates);
     }
 
     @Override
diff --git a/library/src/main/java/com/pengrad/telegrambot/request/SendInvoice.java b/library/src/main/java/com/pengrad/telegrambot/request/SendInvoice.java
index 94431957..7714bd0f 100644
--- a/library/src/main/java/com/pengrad/telegrambot/request/SendInvoice.java
+++ b/library/src/main/java/com/pengrad/telegrambot/request/SendInvoice.java
@@ -12,7 +12,7 @@ public SendInvoice(Integer chatId, String title, String description, String payl
                        String startParameter, String currency, LabeledPrice... prices) {
         super(chatId);
         add("title", title).add("description", description).add("payload", payload).add("provider_token", providerToken)
-                .add("start_parameter", startParameter).add("currency", currency).add("prices", serialize(prices));
+                .add("start_parameter", startParameter).add("currency", currency).add("prices", prices);
     }
 
     public SendInvoice providerData(String providerData) {
diff --git a/library/src/main/java/com/pengrad/telegrambot/request/SendMediaGroup.java b/library/src/main/java/com/pengrad/telegrambot/request/SendMediaGroup.java
index 8548e3c2..41994524 100644
--- a/library/src/main/java/com/pengrad/telegrambot/request/SendMediaGroup.java
+++ b/library/src/main/java/com/pengrad/telegrambot/request/SendMediaGroup.java
@@ -15,7 +15,7 @@ public class SendMediaGroup extends BaseRequest<SendMediaGroup, MessagesResponse
 
     public SendMediaGroup(Object chatId, InputMedia... media) {
         super(MessagesResponse.class);
-        add("chat_id", chatId).add("media", serialize(media));
+        add("chat_id", chatId).add("media", media);
 
         for (InputMedia m : media) {
             Map<String, Object> attachments = m.getAttachments();
diff --git a/library/src/main/java/com/pengrad/telegrambot/request/SetWebhook.java b/library/src/main/java/com/pengrad/telegrambot/request/SetWebhook.java
index c4c733b2..f149ea1c 100644
--- a/library/src/main/java/com/pengrad/telegrambot/request/SetWebhook.java
+++ b/library/src/main/java/com/pengrad/telegrambot/request/SetWebhook.java
@@ -35,7 +35,7 @@ public SetWebhook maxConnections(int maxConnections) {
     }
 
     public SetWebhook allowedUpdates(String... allowedUpdates) {
-        return add("allowed_updates", serialize(allowedUpdates));
+        return add("allowed_updates", allowedUpdates);
     }
 
     @Override