SiO2 was loaded to TiO2 by sol-gel method, and the resulting SiO2/TiO2 was calcined at different temperatures. The loading Of SiO2 improved photocatalytic activity of TiO2. The optimum calcination temperature was 300 degrees C, and the optimum amount of loaded SiO2 was 1.5-4.8 wt.%. This modified photocatalyst was tested for the degradation of nitrobenzene (NB), benzyltrimethylammonium chloride (BTMA), phenol and propionic acid. The highest effect was observed for BTMA, and attributed to electrostatic interaction between BTMA and SiO2/TiO2. Whereas simple mechanical mixing of TiO2 and SiO2, was not effective. (c) 2005 Elsevier B. V. All rights reserved.