This volume contains the proceedings of the 22nd International Conference on Application and Theory of Petri Nets. The aim of the Petri net conferences is to create a forum for discussing progress in the application and theory of Petri nets. Typically, the conferences have 100{150 participants { one third of these coming from industry while the rest are from universities and research institutions. The conferences always take place in the last week of June. This year the conference was organized jointly with the 2nd International Conference on Application of Concurrency to System Design (ICACSD 2001). The two conferences shared the invited lectures and the social program. The conference and a number of other activities are co-ordinated by a steering committee with the following members: G. Balbo (Italy), J. Billington (Aust- lia), G. De Michelis (Italy), C. Girault (France), K. Jensen (Denmark), S. - magai (Japan), T. Murata (USA), C.A. Petri (Germany; honorary member), W. Reisig (Germany), G. Rozenberg (The Netherlands; chairman), and M. Silva (Spain). Other activities before and during the 2001 conference included tool dem- strations, a meeting on \XML Based Interchange Formats for Petri Nets", - tensive introductory tutorials, two advanced tutorials on \Probabilistic Methods in Concurrency" and \Model Checking", and two workshops on \Synthesis of Concurrent Systems" and \Concurrency in Dependable Computing". The tu- rial notes and workshop proceedings are not published in these proceedings, but copies are available from the organizers.