The aim of this work is to analyze the hydrodynamic/electrochemical performance of a solid oxide fuel cell operating on nitrogen diluted hydrogen/oxygen mixture. In this respect, a three-dimensional numerical model of a single-chamber solid oxide fuel cell (SC-SOFC) is developed. The model incorporates the coupled effects of fluid flow in a rectangular duct with mass transport in porous electrodes, selective electrochemical reactions (i.e. hydrogen oxidation on anode and oxygen reduction on cathode) on individual electrodes while operating on nitrogen diluted hydrogen-oxygen mixture. Results show the effect of depletion of gaseous mixture due to hydrogen and oxygen consumption along the flow direction. The model can predict hydrodynamic/electrochemical effects by varying the porosity of the gas diffusion electrodes/catalyst layers. The model is formulated in COMSOL Multiphysics 3.4, a commercial Finite Element Method (FEM) based software package. (c) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.