Hydrodynamics of gases in the cathode of a proton exchange membrane fuel cell that is contacted to an interdigitated gas distributor are investigated using a steady-state multicomponent transport model. The model describes the two-dimensional flow patterns and the distributions of the gaseous species in the porous electrode and predicts the current density generated at the electrode and membrane interface as a function of various operating conditions and design parameters. Results from the model Shown that, with the forced flow-through condition created by the interdigitated gas distributor design, the diffusion layer is greatly reduced. However, even with a much thinner diffusion layer, diffusion still plays a significant role in the transport of oxygen to the reaction surface. The results also show that the average current density generated at an air cathode increases with higher gas flow-through rates, thinner electrodes, and narrower shoulder widths between the inlet and outlet channels of the interdigitated gas distributor.