A process planning model is developed in conjunction with a genetic algorithm. The model first receives the flow network description of possible process plans. The goal is to find the best plan according to some prescribed objective criteria. A novel stage binary matrix format is then applied to describe each stage in a how network. This formulation allows proper representation of possible routes as binary strings to be used by a genetic algorithm. Each string is directly mapped onto a zero/one stage matrix. A ''zero'' bit in these strings represents no connection between two nodes in the flow network, whereas a ''one'' bit denotes a connection between the corresponding nodes. The binary stage matrix representation also facilitates the employment of a modification procedure to ensure that a single distinct path (indication of a process plan) exists in each individual network. The model, developed in the paper, is first illustrated using a simple network. The performance of the computer program based on this model is then evaluated for different sizes of networks.