A field-test of a 20 kW apparatus for adsorptive desiccant air conditioning has been carried out at the Biochemical Engineering Laboratory, Kumamoto University. In the system, operated in a ventilation mode, supply fresh air is dried in a thermal swing honeycomb rotor dehumidifier, and cooled by a regenerative heat exchanger and an evaporative cooler. Return air is used as a cooling medium in the regenerative heat exchanger, and then heated by hot water in a finned coil heater and discarded through the honeycomb rotor dehumidifier after desorbing the moisture adsorbed from the supply air stream, The performance of the present cooling system is examined at regeneration air temperature as low as 80 degrees C, the amount of enthalpy of shout 16.5 kJ/kg can be reduced from the room with the COP (thermal coefficient of performance) of 61% at the superficial air velocity of 1 m/s, Changes in state of air during processing are discussed in terms of a psychrometric diagram.