The thermal conductivity of metal hydride powders and the heat transfer coefficients between metal hydride powder beds and the walls of reaction beds are usually low. When metal hydride powders are used in practical applications, heat transfer enhancement techniques have to be generally applied. Here, expanded natural graphite/metal hydride compacts are described, possessing a high-effective thermal conductivity. Furthermore, the heat transfer coefficient between expanded natural graphite pellets and the inner surface of the surrounding steel tube has been investigated. (C) 2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.