First-principles calculations based on density functional theory are carried out to study the effect of Li decorated boron sheets (BST) on hydrogen storage. The results show that physisorption of H-2 molecules on a pristine BST gives a binding energy of similar to 0.10 eV/H-2, which is too lower for hydrogen storage application. With Li atoms decorated on the both sides of each hexagonal ring, the average binding energy of H-2 can reach similar to 0.35 eV/H-2, acceptable for reversible H-2 adsorption/desorption near the room temperature. The maximal hydrogen storage capacity is 9.22 wt%. The enhanced binding energy of H-2 molecules on the Li decorated BST can be attributed to the orbital hybridizations and polarization mechanisms. (C) 2012 Elsevier B. V. All rights reserved.