Abstract: A theoretical, along-the-channel model, in which momentum transfer,mass transfer and electrode reactions of cathode gases were taken in consideration,was developed to design cathode channels for H₂/O₂ proton exchange membrane fuel cell. The 2-D problem was converted into 1-D problem, and this was implemented by solving the resultant ordinary differential equation with a straightforward shooting computational scheme. With this design tool, the height and length of the channel can be easily designed. An analysis of the effects of main operation and design parameters on the distributions of concentration, velocity and current density was conducted.