Pd nano-octahedron absorbs hydrogen gas faster than Pd nano-cube. This means that H-absorption rate of Pd nanoparticles can be controlled by their structural design. For further design of nano materials for H-absorption, it is important to understand tuning mechanism of H-absorption achieved in shape-controlled Pd nano particles. In this study, kinetics of H-absorption into Pd nano-octahedron and Pd nano-cube were investigated by electronic structure calculation and molecular dynamics simulation. Both simulations well support experimental observation. It was clarified that the shape dependency in H-absorption of the Pd nanoparticles originates from difference in H-invasion process from surface to the inside. (C) 2015 Elsevier B.V. All rights reserved.