A proton exchange membrane (PEM) fuel cell with interdigitated flow field was studied numerically. A three-dimensional, gas-liquid two-phase flow and transport model was developed and utilized to simulate the multi-dimensional, multi-phase flow and transport phenomena in both the anode and cathode sides in the fuel cell and the cell performances with different influencing operational and geometric parameters. The simulations are presented with an emphasis on the physical insight and fundamental understanding afforded by the detailed distributions of working media velocity, oxygen concentration, water vapor concentration, liquid water concentration, water content in the PEM, net water flux per proton flux, current density and overpotential. Cell performances with different influencing factors are also discussed. A comparison of the model prediction and the experimental data shows good agreement. (C) 2008 Elsevier Ltd. All rights reserved.