In this work we present a 3D computational model of a proton exchange membrane fuel cell (PEMFC) to investigate the effect of employing different modes of gas feeding on distributions. The model is based on a commercial fuel cell with serpentine flow-field. From a rigorous analysis of species concentration, current density and ionic conductivity distributions a correct form of feeding gases in the fuel cell is determined. Optimal operating conditions are found for a better utilization of fuel. Simulation results reveal that local current distribution on catalyst layer can be improved by feeding gases in similar mode and changing the channel height. However, polarization curves present an opposite response to this result. The polarization curve obtained in simulation is well correlated with experimental data. (C) 2011 Elsevier B.V. All rights reserved.