The photocatalytic activity and the promoting effect of titania (TiO2) incorporated with carbon black (CB) for removing the pollutant in wastewater were investigated. The TiO2/CB composite photocatalysts with various ratios of TiO2 to CB were prepared by the sol-gel method. The degradation of methyl orange (MO), as the model reaction, was carried out in the aqueous slurry solution using these photocatalysts at 20 degrees C. Experimental results reveal that the ratio of TiO2 to CB largely affected the performance of composite catalyst. An optimal weight ratio of 1 for the highest photocatalytic capability was found. The photocatalytic performances of TiO2/CB catalysts were also found better than those of TiO2 incorporated with activated carbon. The better promoting effect might be attributed to the larger pores of CB which allow a faster diffusion of the adsorbed MO from CB toward TiO2 and the high electrical conductivity of CB which can reduce the recombination of electrons and holes generated in TiO2. (C) 2009 Elsevier B. V. All rights reserved.