The polymer electrolyte membrane fuel cell (PEMFC) using reformate gas as fuel is regarded as an attractive solution for the near-term introduction of fuel cells in stationary or mobile power generation market. With respect to hydrogen feeding, the reformate gas fuelling involves additional polarization losses because of the hydrogen dilution and the impurities contained in the gas. In this paper a one-dimensional model has been developed to investigate the behaviour of a PEMFC operating with reformate gas mixture. The model, based on a semi-empirical approach, considers the kinetic reactions in the anode side taking into account the effect of reverse water-gas shift (RWGS) due to the presence of CO, in the fuel. As it is well known, the exhaust stream from fuel reformers can contain a high carbon dioxide concentration (> 20%) that can have a detrimental effect on the fuel cell performance because of the combination of the dilution and the formation of CO by the RWGS reaction. The numerical Simulation results have been compared with the experimental data, obtained in the test room of Industrial Engineering Department of Cassino University, and a good match has been observed. The model has been developed by using a simplified approach that, nevertheless, can allow to obtain a good numerical prediction of the fuel cell performance reducing the simulation time and computational efforts. Copyright (c) 2008 John Wiley & Sons, Ltd.