In order to save energy and decrease environmental impacts of thermal energy utilization systems, a CaO/H2O/Ca(OH)(2) chemical heat pump (CHP) can be used for high-density heat storage and the cooling/heating functions. In this paper, the performance of the CHP for distinctive functions was examined in comparison with that of the other heat pumps based on the authors' experimental and theoretical studies over ten years on the CaO/H2O/Ca(OH)(2) CHPs. As a result, the CaO/H2O/Ca(OH)(2) CHPs are found to work more efficiently than other types of heat pumps for wider operating temperature ranges in appropriate heat source conditions. (C) 2003 Elsevier Ltd. All rights reserved.