Looking at the GstAppSink code i found that i actually have to override the finalize function on the GObject class. Sorry to bother, I'm not very used with Gobject :-). The GstAppSink code (on the class init function): GObjectClass *gobject_class = (GObjectClass *) klass; GstBaseSinkClass *basesink_class = (GstBaseSinkClass *) klass; gobject_class->dispose = gst_app_sink_dispose; gobject_class->finalize = gst_app_sink_finalize; <div class="gmail_quote">On Thu, Oct 29, 2009 at 11:59 AM, Tiago Katcipis <<a href="mailto:katcipis@inf.ufsc.br">katcipis@inf.ufsc.br</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> I'm building an element that uses an external lib, and when my element is freed (it ref count reaches zero), i want to free some stuff of the external lib i use. I didn't find anything about a generic destructor function that i can override, so when my element is being freed i can free the resources that i was using on my plugin. Can anyone help me? best regards, Katcipis </blockquote></div>