Holonic manufacturing systems (HMS) can be modeled as multi-agent systems to which contract net protocol can be effectively and robustly applied. However, the lack of analysis capability of contract nets makes it difficult to avoid undesirable states such as deadlocks in HMS. This paper presents a framework to model and control HMS based on fusion of Petri net and multi-agent system theory. The main results include: (1) a multi-agent model and a collaboration process to form commitment graphs in HMS based on contract net protocol, (2) a procedure to convert commitment graph to collaborative Petri net (CPN), and (3) feasible conditions and collaborative algorithms to award contracts in HMS based on CPNs. (C) 2003 Elsevier Ltd. All rights reserved.