Nevermind, that was really a stupid question... Anyway I found out where the stackoverflow occurs! Loading the hashmap as maximum as possible as I was trying to do was right, but I wasn't initializing internal collections of my complex objects before serialization. Once all collections of my objects of type MItem are initialized, serializing a HashMap that contains them becomes an impossible operation. Disabling passivation was in my plans anyway. Thanx for the hints Cubert. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4168979#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...