Environmental concerns and the rising energy cost necessitate looking for renewable energy driven environmentally benign adsorption cooling systems. Solar powered adsorption chillers with non-concentrating flat plate or evacuated tube collectors face the problem of not getting adequate driving source temperature during some months of the year. Multi-staging of the adsorption cycle is then needed to exploit the low driving source temperature. A simulation study of a solar thermal driven dual-mode, four-bed silica gel water adsorption chiller is undertaken in this work. The solar thermal collector data of Durgapur (23.48 degrees N, 87.32 degrees E), India has been used as the heat source for the dual-mode chiller. For a driving source temperature above 60 degrees C, the chiller works as a single stage four-bed adsorption chiller; while the chiller functions as a two stage adsorption chiller when the driving source temperature falls below 60 degrees C. With a cooling water temperature of 30 degrees C, this two stage chiller has been found to produce cooling effect with a driving source temperature as low as 40 degrees C. Results indicate that the dual-mode chiller is capable of providing cooling throughout the year under the climatic condition of Durgapur, India. (C) 2013 Elsevier Ltd. All rights reserved.