The storage of hydrogen in hydride materials is currently much researched as a mean of energy storage. This reversible storage is achieved by successive hydriding and dehydriding reactions. During these reactions, the material undergoes structural transformations which result in swelling of the hydride powder grains due to the absorption of hydrogen. This phenomenon can generate major mechanical stresses on the cell containing the hydride. The present experimental study examines the cyclic swelling of a granular bed consisting of hydride Ti-Cr-V + Zr-Ni. Two superimposed phenomena are identified: a cyclic rearrangement causing a reduction and then an increase in porosity coupled with gradual densification of the stack. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.