In order to promote the low-temperature heat-generation of a Chemical Heat Pump unit using a CaO/H2O/Ca(OH)(2) reaction, the design and experimental testing of the Chemical Heat Pump unit for practical use were carried out. In particular, from the viewpoint of heat and mass transfer effects, the effects of apparatus design and heat-exchange condition on the low-temperature heat-generating characteristics were studied. The mass transfer of steam in the reactor was enhanced by spreading the steam way between the particle - tray and the reactor wall, and the heat-generation was promoted. It is also considered that high steam pressure due to the lower inlet of the reactor enhances the reaction and the heat generation. The temperature of the heat-exchanging medium in the reactor was found to affect both the reactivity of CaO and the reaction-equilibrium pressure, and the balance of them decides the generated-temperature-level and the heat-generating rate.