A desiccant cooling process equipped with a multi-divided adsorption dehumidifier is proposed to achieve double stage dehumidification in one adsorbent rotor. In this process, once dehumidified and cooled air is dehumidified again at a different adsorption zone of the same desiccant rotor. It has been found experimentally that dehumidifying performance is strongly influenced by the supply position of outside air to the adsorbent rotor. Humid outside air should be supplied to the latter half of the adsorption zone and once dehumidified air should be sent to the first half of the adsorption zone to maintain a suitable adsorption capacity and rate for the whole adsorption zone. Consideration of the appropriate outside air inlet position and the optimal rotation speed yields a 30% larger amount of dehumidification than that of conventional processes under a humid summer condition.