Microporous metal organic frameworks (MMOFs) have garnered great attraction as adsorbent materials for on-board hydrogen storage. To enhance hydrogen adsorption, we have carried out a systematic study to synthesize, characterize, and modify crystal structures of a number of MMOFs and to investigate their pore characteristics. In addition, their hydrogen adsorption properties at cryogenic and ambient temperature over a range of pressures are analyzed. Copyright (c) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.