A polarization model for a solid oxide fuel cell (SOFC) with a mixed ionic and electronic conductor (MIEC) electrolyte is developed based on charge transport equation and a constant ionic conductivity assumption. The electrochemical reaction at the electrode is described by the Butler-Volmer equation and the energy conservation equation is included as an additional condition to complete the model. The modeling results agree well with experimental data. Utilizing this model the effects of key parameters, including conductivities of electrolyte, electrolyte thickness and cathode exchange current density on the performance of the SOFC are analyzed. The distribution of oxygen partial pressure in the electrolyte is also obtained. (C) 2014 Elsevier B.V. All rights reserved.