Abstract: A chemisorption thermal system provides a cooling output by revolving an array of thermal elements through heat sink and heat source temperature zones defined within a cylindrical housing. Each thermal element is an enclosed elongated body having an absorbent material at one end and a reactant containing part at the other end. Reactant is desorbed from the absorbent material in one part of the thermal cycle, and then evaporated from the reactant containing part to provide a cooling output in another part of the cycle. It is particularly suitable as a vehicle air conditioner using the engine waste heat as a heat source and the vehicle radiator as a heat sink. The invention also makes use of dry chemical absorbent materials which have high heats of reaction allowing the system to have a high heat capacity and low volume. The thermal cycle may be reversed to provide a heating output.