diff --git a/src/main/java/com/corundumstudio/socketio/AckCallback.java b/src/main/java/com/corundumstudio/socketio/AckCallback.java
index 12677cc..472491e 100644
--- a/src/main/java/com/corundumstudio/socketio/AckCallback.java
+++ b/src/main/java/com/corundumstudio/socketio/AckCallback.java
@@ -25,19 +25,26 @@ package com.corundumstudio.socketio;
  */
 public abstract class AckCallback<T> {
 
-    protected Class<T> resultClass;
-    protected int timeout = -1;
+    protected final Class<T> resultClass;
+    protected final int timeout;
 
+    /**
+     * Create AckCallback
+     *
+     * @param resultClass - result class
+     */
     public AckCallback(Class<T> resultClass) {
-        this.resultClass = resultClass;
+        this(resultClass, -1);
     }
 
     /**
-     * Creates AckCallback
+     * Creates AckCallback with timeout
      *
+     * @param resultClass - result class
      * @param timeout - callback timeout in seconds
      */
-    public AckCallback(int timeout) {
+    public AckCallback(Class<T> resultClass, int timeout) {
+        this.resultClass = resultClass;
         this.timeout = timeout;
     }
 
diff --git a/src/main/java/com/corundumstudio/socketio/PacketListener.java b/src/main/java/com/corundumstudio/socketio/PacketListener.java
index 071eb29..04fb785 100644
--- a/src/main/java/com/corundumstudio/socketio/PacketListener.java
+++ b/src/main/java/com/corundumstudio/socketio/PacketListener.java
@@ -15,6 +15,7 @@
  */
 package com.corundumstudio.socketio;
 
+import com.corundumstudio.socketio.ack.AckManager;
 import com.corundumstudio.socketio.namespace.Namespace;
 import com.corundumstudio.socketio.namespace.NamespacesHub;
 import com.corundumstudio.socketio.parser.Packet;
diff --git a/src/main/java/com/corundumstudio/socketio/SocketIOPipelineFactory.java b/src/main/java/com/corundumstudio/socketio/SocketIOPipelineFactory.java
index 85be842..05e0331 100644
--- a/src/main/java/com/corundumstudio/socketio/SocketIOPipelineFactory.java
+++ b/src/main/java/com/corundumstudio/socketio/SocketIOPipelineFactory.java
@@ -34,6 +34,7 @@ import org.jboss.netty.handler.ssl.SslHandler;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import com.corundumstudio.socketio.ack.AckManager;
 import com.corundumstudio.socketio.handler.AuthorizeHandler;
 import com.corundumstudio.socketio.handler.PacketHandler;
 import com.corundumstudio.socketio.handler.ResourceHandler;
diff --git a/src/main/java/com/corundumstudio/socketio/VoidAckCallback.java b/src/main/java/com/corundumstudio/socketio/VoidAckCallback.java
index 3730816..c245273 100644
--- a/src/main/java/com/corundumstudio/socketio/VoidAckCallback.java
+++ b/src/main/java/com/corundumstudio/socketio/VoidAckCallback.java
@@ -25,6 +25,10 @@ public abstract class VoidAckCallback extends AckCallback<Void> {
         super(Void.class);
     }
 
+    public VoidAckCallback(int timeout) {
+        super(Void.class, timeout);
+    }
+
     @Override
     public final void onSuccess(Void result) {
         onSuccess();
diff --git a/src/main/java/com/corundumstudio/socketio/AckManager.java b/src/main/java/com/corundumstudio/socketio/ack/AckManager.java
similarity index 85%
rename from src/main/java/com/corundumstudio/socketio/AckManager.java
rename to src/main/java/com/corundumstudio/socketio/ack/AckManager.java
index 9c3a4e7..114c8d6 100644
--- a/src/main/java/com/corundumstudio/socketio/AckManager.java
+++ b/src/main/java/com/corundumstudio/socketio/ack/AckManager.java
@@ -13,9 +13,10 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package com.corundumstudio.socketio;
+package com.corundumstudio.socketio.ack;
 
 import java.util.Map;
+import java.util.Set;
 import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.TimeUnit;
@@ -24,6 +25,10 @@ import java.util.concurrent.atomic.AtomicLong;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import com.corundumstudio.socketio.AckCallback;
+import com.corundumstudio.socketio.Disconnectable;
+import com.corundumstudio.socketio.SocketIOClient;
+import com.corundumstudio.socketio.ack.AckManager.AckEntry;
 import com.corundumstudio.socketio.parser.Packet;
 import com.corundumstudio.socketio.scheduler.CancelableScheduler;
 import com.corundumstudio.socketio.scheduler.SchedulerKey;
@@ -43,6 +48,10 @@ public class AckManager implements Disconnectable {
             return index;
         }
 
+        public Set<Long> getAckIndexes() {
+            return ackCallbacks.keySet();
+        }
+
         public AckCallback<?> getAckCallback(long index) {
             return ackCallbacks.get(index);
         }
@@ -127,7 +136,7 @@ public class AckManager implements Disconnectable {
         if (callback.getTimeout() == -1) {
             return;
         }
-        SchedulerKey key = new SchedulerKey(Type.ACK_TIMEOUT, sessionId);
+        SchedulerKey key = new AckSchedulerKey(Type.ACK_TIMEOUT, sessionId, index);
         scheduler.schedule(key, new Runnable() {
             @Override
             public void run() {
@@ -139,7 +148,13 @@ public class AckManager implements Disconnectable {
 
     @Override
     public void onDisconnect(BaseClient client) {
-        ackEntries.remove(client.getSessionId());
+        AckEntry entry = ackEntries.remove(client.getSessionId());
+        if (entry != null) {
+            for (Long index : entry.getAckIndexes()) {
+                SchedulerKey key = new AckSchedulerKey(Type.ACK_TIMEOUT, client.getSessionId(), index);
+                scheduler.cancel(key);
+            }
+        }
     }
 
 }
diff --git a/src/main/java/com/corundumstudio/socketio/ack/AckSchedulerKey.java b/src/main/java/com/corundumstudio/socketio/ack/AckSchedulerKey.java
new file mode 100644
index 0000000..9a11fc9
--- /dev/null
+++ b/src/main/java/com/corundumstudio/socketio/ack/AckSchedulerKey.java
@@ -0,0 +1,57 @@
+/**
+ * Copyright 2012 Nikita Koksharov
+ *
+ * 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 com.corundumstudio.socketio.ack;
+
+import java.util.UUID;
+
+import com.corundumstudio.socketio.scheduler.SchedulerKey;
+
+public class AckSchedulerKey extends SchedulerKey {
+
+    private final long index;
+
+    public AckSchedulerKey(Type type, UUID sessionId, long index) {
+        super(type, sessionId);
+        this.index = index;
+    }
+
+    public long getIndex() {
+        return index;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = super.hashCode();
+        result = prime * result + (int) (index ^ (index >>> 32));
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (!super.equals(obj))
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        AckSchedulerKey other = (AckSchedulerKey) obj;
+        if (index != other.index)
+            return false;
+        return true;
+    }
+
+}
diff --git a/src/main/java/com/corundumstudio/socketio/parser/Decoder.java b/src/main/java/com/corundumstudio/socketio/parser/Decoder.java
index b73f781..13a828b 100644
--- a/src/main/java/com/corundumstudio/socketio/parser/Decoder.java
+++ b/src/main/java/com/corundumstudio/socketio/parser/Decoder.java
@@ -25,7 +25,7 @@ import org.jboss.netty.buffer.ChannelBuffers;
 import org.jboss.netty.util.CharsetUtil;
 
 import com.corundumstudio.socketio.AckCallback;
-import com.corundumstudio.socketio.AckManager;
+import com.corundumstudio.socketio.ack.AckManager;
 import com.corundumstudio.socketio.namespace.Namespace;
 
 public class Decoder {
diff --git a/src/main/java/com/corundumstudio/socketio/transport/BaseClient.java b/src/main/java/com/corundumstudio/socketio/transport/BaseClient.java
index 72b6f70..d47fd2d 100644
--- a/src/main/java/com/corundumstudio/socketio/transport/BaseClient.java
+++ b/src/main/java/com/corundumstudio/socketio/transport/BaseClient.java
@@ -25,9 +25,9 @@ import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelFuture;
 import org.jboss.netty.channel.ChannelFutureListener;
 
-import com.corundumstudio.socketio.AckManager;
 import com.corundumstudio.socketio.DisconnectableHub;
 import com.corundumstudio.socketio.SocketIOClient;
+import com.corundumstudio.socketio.ack.AckManager;
 import com.corundumstudio.socketio.namespace.Namespace;
 import com.corundumstudio.socketio.parser.Packet;
 import com.corundumstudio.socketio.parser.PacketType;
diff --git a/src/main/java/com/corundumstudio/socketio/transport/FlashSocketTransport.java b/src/main/java/com/corundumstudio/socketio/transport/FlashSocketTransport.java
index c11f0af..f49f3ee 100644
--- a/src/main/java/com/corundumstudio/socketio/transport/FlashSocketTransport.java
+++ b/src/main/java/com/corundumstudio/socketio/transport/FlashSocketTransport.java
@@ -18,10 +18,10 @@ package com.corundumstudio.socketio.transport;
 import org.jboss.netty.channel.ChannelPipeline;
 import org.jboss.netty.channel.ChannelHandler.Sharable;
 
-import com.corundumstudio.socketio.AckManager;
 import com.corundumstudio.socketio.DisconnectableHub;
 import com.corundumstudio.socketio.HeartbeatHandler;
 import com.corundumstudio.socketio.SocketIOPipelineFactory;
+import com.corundumstudio.socketio.ack.AckManager;
 import com.corundumstudio.socketio.handler.AuthorizeHandler;
 
 @Sharable
diff --git a/src/main/java/com/corundumstudio/socketio/transport/WebSocketClient.java b/src/main/java/com/corundumstudio/socketio/transport/WebSocketClient.java
index fc569d1..da38a84 100644
--- a/src/main/java/com/corundumstudio/socketio/transport/WebSocketClient.java
+++ b/src/main/java/com/corundumstudio/socketio/transport/WebSocketClient.java
@@ -20,8 +20,8 @@ import java.util.UUID;
 import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelFuture;
 
-import com.corundumstudio.socketio.AckManager;
 import com.corundumstudio.socketio.DisconnectableHub;
+import com.corundumstudio.socketio.ack.AckManager;
 import com.corundumstudio.socketio.messages.WebSocketPacketMessage;
 import com.corundumstudio.socketio.parser.Packet;
 
diff --git a/src/main/java/com/corundumstudio/socketio/transport/WebSocketTransport.java b/src/main/java/com/corundumstudio/socketio/transport/WebSocketTransport.java
index ac6cfc7..a55416b 100644
--- a/src/main/java/com/corundumstudio/socketio/transport/WebSocketTransport.java
+++ b/src/main/java/com/corundumstudio/socketio/transport/WebSocketTransport.java
@@ -42,13 +42,13 @@ import org.jboss.netty.handler.codec.http.websocketx.WebSocketServerHandshakerFa
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import com.corundumstudio.socketio.AckManager;
 import com.corundumstudio.socketio.CompositeIterable;
 import com.corundumstudio.socketio.Disconnectable;
 import com.corundumstudio.socketio.DisconnectableHub;
 import com.corundumstudio.socketio.HeartbeatHandler;
 import com.corundumstudio.socketio.SocketIOClient;
 import com.corundumstudio.socketio.SocketIOPipelineFactory;
+import com.corundumstudio.socketio.ack.AckManager;
 import com.corundumstudio.socketio.handler.AuthorizeHandler;
 import com.corundumstudio.socketio.messages.PacketsMessage;
 
diff --git a/src/main/java/com/corundumstudio/socketio/transport/XHRPollingClient.java b/src/main/java/com/corundumstudio/socketio/transport/XHRPollingClient.java
index a37cc1a..599ac9a 100644
--- a/src/main/java/com/corundumstudio/socketio/transport/XHRPollingClient.java
+++ b/src/main/java/com/corundumstudio/socketio/transport/XHRPollingClient.java
@@ -20,8 +20,8 @@ import java.util.UUID;
 import org.jboss.netty.channel.Channel;
 import org.jboss.netty.channel.ChannelFuture;
 
-import com.corundumstudio.socketio.AckManager;
 import com.corundumstudio.socketio.DisconnectableHub;
+import com.corundumstudio.socketio.ack.AckManager;
 import com.corundumstudio.socketio.messages.XHRNewChannelMessage;
 import com.corundumstudio.socketio.messages.XHRPacketMessage;
 import com.corundumstudio.socketio.parser.Packet;
diff --git a/src/main/java/com/corundumstudio/socketio/transport/XHRPollingTransport.java b/src/main/java/com/corundumstudio/socketio/transport/XHRPollingTransport.java
index 6d31d98..a7fef7a 100644
--- a/src/main/java/com/corundumstudio/socketio/transport/XHRPollingTransport.java
+++ b/src/main/java/com/corundumstudio/socketio/transport/XHRPollingTransport.java
@@ -40,13 +40,13 @@ import org.jboss.netty.handler.codec.http.QueryStringDecoder;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import com.corundumstudio.socketio.AckManager;
 import com.corundumstudio.socketio.CompositeIterable;
 import com.corundumstudio.socketio.Configuration;
 import com.corundumstudio.socketio.Disconnectable;
 import com.corundumstudio.socketio.DisconnectableHub;
 import com.corundumstudio.socketio.SocketIOClient;
 import com.corundumstudio.socketio.SocketIOPipelineFactory;
+import com.corundumstudio.socketio.ack.AckManager;
 import com.corundumstudio.socketio.handler.AuthorizeHandler;
 import com.corundumstudio.socketio.messages.PacketsMessage;
 import com.corundumstudio.socketio.messages.XHRErrorMessage;
diff --git a/src/test/java/com/corundumstudio/socketio/PacketHandlerTest.java b/src/test/java/com/corundumstudio/socketio/PacketHandlerTest.java
index ad8a7b8..eb8577a 100644
--- a/src/test/java/com/corundumstudio/socketio/PacketHandlerTest.java
+++ b/src/test/java/com/corundumstudio/socketio/PacketHandlerTest.java
@@ -32,6 +32,7 @@ import org.jboss.netty.channel.UpstreamMessageEvent;
 import org.junit.Before;
 import org.junit.Test;
 
+import com.corundumstudio.socketio.ack.AckManager;
 import com.corundumstudio.socketio.handler.PacketHandler;
 import com.corundumstudio.socketio.messages.PacketsMessage;
 import com.corundumstudio.socketio.namespace.Namespace;
diff --git a/src/test/java/com/corundumstudio/socketio/parser/DecoderBaseTest.java b/src/test/java/com/corundumstudio/socketio/parser/DecoderBaseTest.java
index a5de8a0..332dfea 100644
--- a/src/test/java/com/corundumstudio/socketio/parser/DecoderBaseTest.java
+++ b/src/test/java/com/corundumstudio/socketio/parser/DecoderBaseTest.java
@@ -19,8 +19,8 @@ import org.junit.Before;
 
 import mockit.Mocked;
 
-import com.corundumstudio.socketio.AckManager;
 import com.corundumstudio.socketio.Configuration;
+import com.corundumstudio.socketio.ack.AckManager;
 
 
 public class DecoderBaseTest {