A transient, three-dimensional computational investigation of coupled heat and mass transfer in an annular cylindrical hydrogen storage tank, equipped with fins and filled with MmNi(4.6)Fe(0.4), is presented. The effects of different parameters such as length, thickness and thermal conductivity of fins and overall heat transfer coefficient on the hydrogen storage performance of the tank are studied. The predicted hydrogen storage capacity at different supply pressures showed good agreement with the experimental data reported in the literature. In addition, it is observed that the use of fins enhances heat transfer within the hydride bed and consequently 40% improvement of the time required for 90% storage can be achieved over the case without fins. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.