A chemical heat-pump system using two hydrogen-absorbing alloys is proposed to utilize heat exhausted from a high-temperature source such as high-temperature-gas-cooled reactor, HTGR, which is designed to produce H(2) more efficiently. The overall system proposed here consists of HTGR, He gas turbines, chemical heat pumps and reaction vessels corresponding to the three-step decomposition reactions comprising the I-S process, A fundamental research is performed experimentally on heat generation in a single bed packed with a hydrogen-absorbing alloy that works at the H(2) production temperature. The hydrogen-absorbing alloy of Zr(V(1-x)Fe(x))(2) is selected as a material that has a proper plateau pressure for the heat-pump system operated between the input and output temperatures of HTGR. Temperature jump due to heat generated when the alloy absorbs H(2) proves that the alloy-H(2) system can heat up the exhaust gas even at 600 degrees C without any external mechanical force. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.