Optimum operating conditions of a chemical heat pump unit using CaO/H2O reaction were studied for effective utilization of surplus electricity. It is expected that the performance of heat storage is enhanced by improvement of condensation conditions in the condenser. The reactivity of the multi-tray type bed increases because of the enhanced vapor transportation although the packed density decreases. The maximum amount of generated hot heat was 745 MJ/m(3). The heat exchangers need be improved in order to increase the amount of recovered heat. The proposed unit was found to be effective for a hot water supply and cooling system at the temperature levels of the recovered heat: 353 K for hot heat and below 278 K for cold heat.