A desiccant assisted air conditioning apparatus incorporates an absorption heat pump device to produce improved operating efficiency. The heat pump device has circulation units 1 and 2, each of which includes an evaporator, an absorber, a generator and a condenser and heat exchangers provided by heat transfer pipe action. The absorber in unit 1 operates at a higher temperature than the absorber in the absorber in unit 2 so that heat transfer can occur through heat transfer pipes acting as heat exchangers between the first evaporator and the second absorber in the two units. The heat of condensation from units 1 and 2, as well as the heat of absorption from unit 1 are used to heat regeneration air for regenerating the desiccant. The heat of evaporation in unit 2 is utilized to produce chilled water for cooling the process air in the air conditioning apparatus. The use of heat enabled by the heat pump device achieves a high level of energy conservation for performing desiccant assisted air conditioning apparatus which operates at high efficiency.