The aim of this work is to present a two-dimensional transient model, of heat and mass transfer in a proton exchange membrane fuel cell (PEMFC). The model includes various conservation equations such as mass (hydrogen, oxygen, water concentration), Momentum and energy equations this model is combined with the electrochemical model. The objective of this work is to know the hydrogen, oxygen water concentration, temperature and pressure to determine the performance conditions of the fuel cell under the current density and permeability effect. A program based on the finite volume method was performed to simulate these equations system. The numerical results show that the gas distribution in the assembly membrane electrode (MEA) and the power density is affected by the nature of porous middle (permeability). Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.