Abstract: The gas flow characteristic in an adsorbent bed is avital problem for further studying the mechanics of gas separation process.In this paper, a comprehensive mathematical model of gas flow and adsorptionin an adsorbing bed, which based on mass and momentum conservation law, isestablished. A typical cyclic process of an axial-flow rapid pressure swingadsorption is numerically studied. The flow patterns in different cyclicperiod for pressurization, adsorption, depressurization, desorption andpurge, are obtained. The flow characteristics and their difference from thegas flow in an empty bed and a no-adsorption bed are also studied.