A numerical model for an anode-supported intermediate-temperature direct-internal-reforming planar solid oxide fuel cell (SOFC) was developed. In this model, the volume-averaging method is applied to the flow passages in the SOFC by assuming that a porous material is inserted in the passages as a current collector. This treatment reduces the computational time and cost by avoiding a full three-dimensional simulation while maintaining the ability to solve the flow and pressure fields in the streamwise and spanwise directions. In this model, quasi-three-dimensional multicomponent gas flow fields, the temperature field, and the electric potential/current fields were simultaneously solved. The steam-reforming reaction using methane, the water-gas shift reaction, and the electrochemical reactions of hydrogen and carbon monoxide were taken into account. It was found that the endothermic steam-reforming reaction led to a reduction in the local temperature near the inlet and limited the electrochemical reaction rates therein. Computational results indicated that the local temperature and current density distributions can be controlled by tuning the pre-reforming rate. It was also found that a small amount of heat loss from the sidewall can cause significant nonuniformity in the flow and thermal fields in the spanwise direction. (C) 2010 Elsevier Ltd. All rights reserved.