You're trying to communicate with a cache in a remote VM. All the business with binding a proxy to the cache in JNDI and then looking up the proxy on the client side just gives your client an object to invoke on that implements the PojoCacheMBean interface and that will make remote calls back to the server. But the putObject() is still a remote call -- any object you pass has to be serialized for the remote call and thus has to implement Serializable. If you want PojoCache to handle this for you, you need to instantiate an instance of the cache on the client side, and have it cluster with the one on the server side. You can then call putObject() against a real cache, rather than a proxy. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4046842#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...