A fully coupled CFD model of a direct internal reforming single cell SOFC stack previously designed by Ceramic Fuel Cell Ltd (CFCL) has been developed. In this model, an innovative solution technique for accelerating finite volume treatment of the electrodes as two distinct layers, a diffusion layer and a catalyst layer, is taken to analyse the combined effects of the macro/microstructural parameters on distribution of fields and each of the reactions involved in the process. To assess the simulation results, the model is not only evaluated with the CFCL experimental data that was reported from the similar geometry, but it is also assessed for the effects of the reforming and water gas shift reactions. It is found that a 3D model is more representative of the global reforming reaction rate. Furthermore, distributions of the key parameters along different spatial domains disclose the complex interaction between the anode flow field design and microstructural parameters of the anode diffusion layer. In fact, an optimal set of the anode microstructure that promotes the reforming reaction rate will not automatically result in improved SOFC performance. The developed model is a powerful tool to study complex fuel cell related problems and to optimize fuel cells' structure. Crown Copyright (c) 2013 Published by Elsevier B.V. All rights reserved.