Nowadays, energetic needs are mainly covered by fossil energies leading to pollutant emissions mostly responsible for global warming. Among the different possible solutions for the greenhouse effect reduction, hydrogen has been proposed for energy transportation. Indeed, H-2 can be seen as a clean and efficient energy carrier. However, beside the difficulties related to hydrogen production, efficient high capacity storage is still to be developed. Hydrogen can be stored as a compressed gas, in liquefied tanks or absorbed in solids. Many metals and alloys are able to store large amounts of hydrogen. This latter solution is of interest in terms of safety, global yield and long time storage. However, to be suitable for applications, such compounds must present high capacity, good reversibility, fast reactivity and sustainability. In this paper, we will review on the structural and thermodynamic properties of metallic hydrides. Their solid-gas hydrogenation behaviour and the related absorption-desorption isotherm curves are examined as a useful criterion for the selection of suitable materials for applications. The storage performances obtained with these alloys are reported and some solutions to common problems such as corrosion, passivation, decrepitation, poor kinetic and short cycle life are discussed. (C) 2003 Elsevier Ltd. All rights reserved.