This paper presents a hydrogen storage system using metal hydrides for a combined heat and power (CHP) system. Hydride storage technology has been chosen due to project specifications: high volumetric capacity, low pressures (< 3.5 bar) and low temperatures (< 75 degrees C: fuel cell temperature). During absorption, heat from hydride generation is dissipated by fluid circulation. An integrated plate-fin type heat exchanger has been designed to obtain good compacity and to reach high absorption/desorption rates. At first, the storage system has been tested in accordance with project specifications (absorption/desorption 3.5/1.5 bar). Then, the hydrogen charge/discharge times have been decreased to reach system limits. System design has also been modelled in order to simulate thermal and mass behaviour of the storage tank. The model is based on Fluent software. We take into account heat and mass transfers in the porous media and a convective flow required to cool/heat the system during absorptions/desorptions. The thermal and mass behaviour of the hydride has been integrated in the software. The heat and mass transfers experimentally obtained have been compared to results calculated by the model. (C) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.