A new method to enhance photocatalytic performance of TiO2 by dispersing it onto hydrophilically surface modified carbon nanotubes is reported. The hydrophilically surface functionalized CNTs and as prepared composite CNTs-TiO2 photocatalysts were characterized using FT-IR, XPS, XRD, BET adsorption analysis and TEM. The composite samples were evaluated for their photocatalytic activity toward the degradation of methyl orange in aqueous solution under both UV and visible light irradiation. The results indicated that the hydrophilic functional groups were grafted covalently on the surface of CNTs successfully, and the functionalized CNTs exhibit higher BET specific surface area and aquatic solubility. The improved photocatalytic activity of CNTs-TiO2 was mainly attributed to the high dispersion of TiO2 on CNTs and the intimate contact between TiO2 and CNTs resulting in dense heterojunctions at the interface of TiO2 and CNTs. (C) 2011 Elsevier B. V. All rights reserved.