While utilizing biogas in Solid Oxide Fuel Cell (SOFC) systems equipped with either internal or external catalytic domain possessing a uniform catalytic activity, the rate of the reforming reaction significantly changes along the flow field due to the rapid conversion of the methane in the inlet region. Thus, a dramatic temperature variation develops along the flow field, resulting in thermal stress on the adjacent components. To mitigate the temperature variation, design of a catalytic domain graded in terms of the catalyst loading along the flow field is a promising solution, for which herein we present a strategy based on numerical modeling and in situ temperature measurement along the reformer. We design a graded catalytic domain for a uniform temperature distribution and demonstrate it experimentally, aiming the efficient use of biogas in SOFC systems. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.