The regeneration of silica gel desiccant by a solar air heater for use in an air-conditioning system has been investigated. The hot air is produced by a compound 2 parabolic concentrator collector (CPC), which has aperture and receiver areas 1.44 and 0.48 m(2), respectively. The regeneration temperature can be started at 40 degrees C. The regeneration rate and the regeneration efficiency were greatly affected by the solar radiation, but depended only slightly on the different initial moisture contents of silica gel and the number of silica gel beds. The regeneration of silica gel provided by the CPC collector is suitable for a tropical climate where the diffuse solar radiation is high all the year round. (c) 2006 Elsevier Ltd. All rights reserved.