MFI zeolite membranes were synthesized on porous alpha-alumina hollow fibers by in-situ hydrothermal synthesis. The membranes were further modified for H-2 separation by on-stream catalytic cracking deposition of methyldiethoxysilane (MDES) in the zeolitic pores. The separation performance of the modified membranes was characterized by separation of H-2/CO2 gas mixture at 500 degrees C. Activation of MFI zeolite membranes by air at 500 degrees C was found to promote catalytic cracking deposition of silane in the zeolitic pores effectively, which resulted in significant improvement of H-2-separating performance. The H-2/CO2 separation factor of 45.6 with H-2 permeance of 1.0 x 10(-8) mol m(-2) s(-1) Pa-1 was obtained at 500 degrees C for a modified hollow fiber MFI zeolite membrane. The as-made membranes showed good thermochemical stability for the separation of H-2/CO2 gas mixture containing H2O and H2S, respectively. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.