A computational study of hydrogen production by a dimethyl ether reformer combined with a catalytic combustor is conducted to investigate its feasibility for on-board automotive applications. The combined reactor has a stacked channel structure consisting of alternating reformer monoliths and catalytic combustor monoliths on a heat-conducting substrate. The inner surfaces of the walls of each monolith are coated with reforming and combusting catalysts, respectively. The effects of the feeding flow rate, thermal conductivity of the substrate, and porosity of the catalyst layer on the hydrogen production efficiency of the, proposed combined reactor are investigated to determine the optimal design and operating conditions. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.