Both the H-2-H2O and CO-CO2 electrochemical reaction processes as well as the detailed reforming reactions are coherently integrated into the multi-physics transport processes in a direct methane fueled SOFC. The model is verified using experimental polarization curves under the temperatures of 600 degrees C, 650 degrees C and 700 degrees C respectively. Simulation results show that the anode reaction processes are slower than the cathode oxygen reduction process in direct methane fueled SOFCs. The CO-CO2 oxidation process plays an important role, which not only directly influences the cell performance but also affects the internal methane reforming process. The results also show that H2O is able to improve the cell performance through intensifying the methane reforming reactions, while CO and CO2 have relatively small effects. Increasing the inlet methane flow rate is able to improve the cell performance and generate more steam. The generated steam in turn enhances the methane reforming process. Published by Elsevier B.V.