The feasibility to store hydrogen in calcium-decorated metal organic frameworks (MOFs) is explored by using first-principles electronic structure calculations. We show that substitution of boron atoms into the benzene ring of the MOF linker substantially enhances the Ca binding energy to the linker as well as the H(2) binding energy to Ca. The Kubas interaction between H(2) molecules and Ca added in the MOF gives rise to a large number of bound H(2)'s (8H(2)'s per linker) with the binding energy of 20 kJ/mol, which makes the system suitable for reversible hydrogen storage under ambient conditions. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.