A multiscale approach is used to investigate the hydrogen adsorption in nanoporous Zeolite Imidazolate Frameworks (ZIFs) on varying geometries and organic linkers. Ab initio calculations are performed at the MP2 level to obtain correct interaction energies between hydrogen molecules and the ZIF structures. Subsequently, classical grand canonical Monte-Carlo (GCMC) simulations are carried out to obtain the hydrogen uptake of ZIFs at different thermodynamic conditions of pressure and temperature. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.