In order to simulate water transport process in a PEM fuel cell, including membrane swelling effects, this study presents a numerical solution to the complete momentum, species concentration and energy equations for dynamic laminar flow resulting from the combined water content effect, thermal and mass diffusion in the cathode side of a PEM fuel cell. Our objective is to develop a novel approach to investigate the effect of membrane swelling dueto the increase of water content and gas diffusion layer flooding on the performance of PEMFC.