Poisoning effects of sulfur compounds on the performances of solid oxide fuel cells are non-trivial. However, the synergistic effects of gas diffusion, adsorption, desorption and reaction in anodes are typically neglected. In this work, an analytical model is derived to quantitatively evaluate the poisoning effects of H2S. The results show that sulfur poisoning correlates closely with inefficient gas diffusion for small anode pore size, small porosity/tortuosity, and low working temperatures. As compared with concentration polarization, H2S-diffusion-induced activation polarization in thin anodes with a large epsilon/tau is detrimental, especially for low-temperature operations with a high H2S concentration and a low current density. (c) 2017 American Institute of Chemical Engineers