In this paper, the effectiveness factors of Ni/MgAl2O4 washcoat catalyst layers under steam methane reforming (SMR) conditions relevant to small-scale hydrogen production systems (1-3 bar pressure, 600-800 degrees C temperature, and 2-4 steam-to-carbon ratio) are numerically investigated. The effects of the washcoat properties, including the layer thickness (20-80 mu m), the mean pore diameter (10-40 nm), and the volume-specific catalyst surface area (1.1-3.3 x 10(7) m(2)/m(3)), are also considered. The simulation is conducted by fully considering the intrinsic reaction kinetics (Xu and Froment model) and multicomponent mass diffusion (Maxwell-Stefan equation). The numerically obtained effectiveness factors are presented as a function of the methane conversion ratio and effective Thiele moduli, and simple correlation equations are proposed for easy evaluation of the effectiveness factors. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.