A novel bimodal catalytic membrane reactor (BCMR) consisting of a Ru/gamma-Al2O3/alpha-Al2O3 bimodal catalytic support and a silica separation layer was proposed. The catalytic activity of the support was successfully improved due to enhanced Ru dispersion by the increased specific surface area for the gamma-Al2O3/alpha-Al2O3 bimodal structure. The silica separation layer was prepared via a sol-gel process, showing a H-2 permeance of 2.6 x 10(-7) mol Pa-1 m(-2) s(-1), with H-2/NH3 and H-2/N-2 permeance ratios of 120 and 180 at 500 degrees C. The BCMR was applied to NH3 decomposition for COx-free hydrogen production. When the reaction was carried out with a NH3 feed flow rate of 40 ml min(-1) at 450 degrees C and the reaction pressure was increased from 0.1 to 0.3 MPa, NH3 conversion decreased from 50.8 to 35.5% without H-2 extraction mainly due to the increased H-2 inhibition effect. With H-2 extraction, however, NH3 conversion increased from 68.8 to 74.4% due to the enhanced driving force for H-2 permeation through the membrane. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.