The present numerical study aimed at studying the solid-statehydrogen storage and destocking in the Lanthanum Nickel (LaNi5-H-2) in a concentric triple-tube heat exchanger. Moreover, the influence of the thermal-reactor geometry for the storage and destocking hydrogen have been examined by changing the diameters of the heat exchanger. The performance of Lanthanum Nickel was compared with those of the hydride (MmNi(4.6)Fe(0.4)) and activated carbon. The flowing parameters: kinetics of hydrogen absorption/desorption, chemical reactions, enthalpy of fusion, equilibrium pressure, hydrogen concentration and the storage capacity were considered for calculating the terms of mass and energy equations. The hydride thermal and mass behaviour was integrated in the CFD Fluent with software (C++). A good agreement between the presented model and the literature experimental results was obtained. Additionally, the mentioned above parameters have shown a significant impact on the geometry of the reactor. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.