A mathematical model describing the multi-component species transport inside the porous solid oxide fuel cell (SOFC) anode has been developed. The model includes the water-gas shift reaction in the anode electrode (backing) layer and the spatially resolved electrochemical reaction in the reaction zone layer. The modified Stefan-Maxwell equations incorporating Knudsen diffusion were used to model multicomponent diffusion inside the porous electrode (backing) and reaction zone layers. Moreover, the general Butler-Volmer equation was used to model the electrochemical reaction in the reaction zone layer. The model can predict the distribution of species within the SOFC anode for any reformate gas composition involving carbon dioxide, carbon monoxide, hydrogen and water vapour. The chemical and electrochemical reactions as well as transport processes in the SOFC anode can be simulated, yielding the anode performance under various operating and design conditions. This anode model can be coupled with a similarly developed model for the cathode to form an overall model for a single SOFC model. Copyright (c) 2005 John Wiley & Sons, Ltd.