The aim of this paper was to verify and validate an object-oriented design using Petri nets. We were interested to apply Petri net-based rapid prototyping of parallel and distributed systems with three majors steps: modeling, analysis, and verification and validation of the object-oriented design. There was a great desire to utilize a tool having a graphical interface for the Petri Net presentation. The design chosen was that of a bank ATM machine. This design was developed by Wirfs-Brock, Wilkerson, and Wiener [4]. The tool selected for use was SYROCO [2]. This tool provides a means to define Co-operative objects (COO). The COO language uses high-level Petri Nets to model the internal operation of objects, and provides a mechanism to connect together the Petri nets of distinct objects via the normal Object Oriented interface.