A model for piston driven, rapid pressure swing reactor is developed. Boundary conditions are presented based on the continuity requirements for pressure, velocity and concentration at the inlet of catalyst bed. 2A↔B + C is employed as a working reaction system in which only C, not A or B, is adsorbed. By using dynamic simulation software gPROMS, the influences of bed length, cycle length, piston moving velocity, product delivery velocity and basal pressure on reaction and separation efficiency are investigated.