An SBA-15/carbon molecular sieve (CMS) composite membrane, using polyetherimide as a precursor and mesoporous silica as filler, was fabricated for hydrogen separation. The effect of mesoporous SBA-15 on the gas transport properties of the composite membrane was evaluated. The permeability and selectivity coefficients of H-2, CO2, O-2, N-2, and CH4 were estimated for the pure CMS and SBA-15/CMS composite membranes at a feed pressure of 2-7 atm for 30 degrees C. The SBA-15/CMS composite membrane had a gas permeability higher than that of the pure CMS membrane, whereas its selectivity was the same. The permeability was found to be independent of pressure; this indicates that the gases are transported through the membrane by a molecular sieve mechanism. The membranes appeared to have a more microporous structure when the mesoporous silica SBA-15 was incorporated. These results concur with the hypothesis that SBA-15 improves gas diffusivity by increasing pore volume. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.