Nowadays, adsorption heat pumps receive considerable attention as they are energy savers and environmentally benign. In this study silica gel-water is taken as the adsorbent refrigerant pair. To exploit solar/waste heat of temperatures below 70 degreesC, staged regeneration is necessary. A new two-stage non-regenerative adsorption chiller design and experimental prototype is proposed. Experimental temperature profiles of heat transfer fluid inlets and outlets are presented. The two-stage cycle can be operated effectively with 55 degreesC solar/waste heat in combination with a 30 degreesC coolant temperature. In this paper the physical adsorption of silica gel, working principle and features of a two-stage chiller are described. (C) 2000 Elsevier Science Ltd. All rights reserved.