In this study, a two-dimensional micro/macroscale model is developed to simulate the operation of anode-supported, planar, intermediate-temperature solid oxide fuel cells (IT-SOFCs) fed with partially reformed methane fuel. The previous micro/macroscale model for hydrogen-fueled IT-SOFCs is extended to take into account the direct internal reforming (DIR) of methane inside the porous cermet anode and the multi-component mass transport and reforming reaction heat consumption. The intrinsic reaction kinetics for steam methane reforming (SMR) at the nickel catalyst surface is fully considered based on the micro/macroscale calculation framework under the assumption of fully-developed laminar channel flow. Using the developed micro/macroscale model, a detailed investigation of the methane-fueled IT-SOFC operation is conducted, followed by parametric studies on the effects of the inlet temperature, the co- or counter-flow configuration, the air flow rate, and the cell length on performance. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.