Silica gel microspheres were prepared by sol-gel process of silicon tetraethoxide in reverse suspension. Subsequently, titanium tetra-2-propoxide solution was added to the system for producing titania gel. The composite microspheres prepared were analyzed with optical microscopy, electron probe microanalysis, and X-ray diffraction. Lowering the titanium alkoxide concentration in the continuous phase was effective to depress the agglomeration of fine titania particles. When the titanium alkoxide solution was divided into four parts and each aliquot was added separately, the covering state with titania became more uniform. The composite microspheres prepared were suspended in dye solution under ultraviolet irradiation and examined for the possibility of treating wastewater. The dye concentration rapidly decreased more than with a commercial titania powder, due to the effects of both photodegradation and adsorption. (C) 2003 Elsevier Science Ltd. All rights reserved.