This invention discloses an extremely simple chemical heat pump system utilizing the chemical reaction heat of a perfectly reversible chemical disassociation reaction system wherein one gaseous compound is involved in the reversible reaction. The present system can realize a large coefficient of performance over a very attractive temperature range and level for general use, by absence of any phase transition. Reaction kinetics of the system are excellent since only one reversible non-flammable gaseous compound is involved in the chemical heat pump system. The system can be provided with a computer controlled system for changing the restriction value of the expansion valve. The system utilizes jet ejectors in combination with the compressor in the same or different loops to reduce the capacity requirements on the compressor.