A steady state, two dimensional mathematical model on PBI fuel cells based on an alternative current(AC) impedance technique is presented. The model mainly accounts for the mass transport and polarization phenomena of the cathode side, and for the first time, the AC impedance technique is combined with the mathematical model to offer a model with two very important electrochemical parameters - internal resistance and apparent area exchange current density. A GUI (graphic user interface) based PBI fuel cell model software is developed to make the model more applicable. O-2 and H2O distributions are calculated and polarization curves are predicted. The simulated results compare well with experimental data. (C) 2007 Elsevier Ltd. All rights reserved.