If your collection class and all its elements are Serializable, you have the option to set the whole aCollection as a variable, or even the parent someBObject, again, if class B is Serializable. This is convenient, but if you don't want your objects stored as binaries, you can provide a Hibernate mapping for class B, add it to the jbpm.hibernate.cfg.xml file, and simply set someBObject as variable. jBPM will recognize Hibernatable objects with either Long or String identifiers and persist them by storing their ID value automatically. Hope this helps.