In the present work, we perform a theoretical study of light metal (Li, Na, and Ca) doping and H-2 adsorption on graphene sheets with N-substituted defects. Through density functional theory calculations, the adsorption energies, density of states, and extent of charge transfer in systems featuring H-2 adsorption on metal-doped species (ideal, pyridinic, and pyrrolic graphene sheets) are obtained, and we determine that both N and metal atoms play important roles in H-2 adsorption. In addition, molecular dynamics simulations are employed to evaluate the nature of H-2 adsorption at room temperature. All computational results indicated that Ca-doped pyrrolic graphene could be expected as a promising candidate for H-2 storage. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.