In this study, the Control-Volume Lattice Boltzmann Method (CVLBM) based on the unstructured grids is proposed as a numerical solver for transient heat and mass transfer in a Metal Hydrogen Reactor (MHR) during the absorption process. To check the validity of the numerical approach, computational results were compared with those of the literature and a good agreement was obtained. The obtained results were also compared with those of the unstructured Control Volume Finite Element Method (CVFEM). We found that the new approach correctly predicts hydrogen absorption phenomena and has less CPU time compared with the CVFEM (about 8 times faster). In addition, various tank geometries were numerically studied and a new geometric configuration is proposed. The dynamic performances of these layouts were compared based on the numerical simulation. We found that the geometrical modification improves the hydriding performance. For the new configuration, we found that the storage time can be reduced by 87% compared to the basic configuration. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.