Metal hydride thermal compression is a reliable process to compress hydrogen without contamination. We report on the development of a three-stage metal hydride hydrogen compressor. It will compress a part of the hydrogen produced by an electrolyser and will recycle the heat released by the electrolytic cells as its principal energy supply. This compressor will raise the hydrogen pressure from 1 to 20 atm, using three hydride compression stages working between 20 and 80 degrees C. This paper describes the design of the prototype and its connections with the electrolyser. We present our data on the AB(5) hydride materials that have been characterized and selected. Also, the construction of a lightweight hydride bed reservoir, developed specially for this application, preliminary results on heat transfer, reaction rate and efficiency, are discussed. (c) 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.