Double-walled carbon nanotube (DWCNT)-TiO2 hybrid was prepared by hydrothermal method and characterized by X-ray diffraction, electron microscopy, N-2-adsorption analysis, Raman spectroscopy, Fourier transform infrared spectroscopy, and UV vis diffuse reflectance spectroscopy. The photocatalytic activity of DWCNT-TiO2 hybrid was tested by the photocatalytic degradation of sulfathiazole. The experimental results showed that the introduction of the DWCNTs provides DWCNT-TiO2 hybrid with visible light-induced photoactivity and a large surface area. The DWCNTs were coated with TiO2 nanoparticles, which generated an intimate contact between the DWCNTs and TiO2. The DWCNT-TiO2 hybrid showed an excellent visible-light-induced activity, compared with multi-walled carbon nanotube-TiO2 and single-walled carbon nanotube-TiO2 hybrids, which can be attributed to the unique electronic structure of the DWCNTs that can work well as not only a photosensitizer but also an electron conductor. In addition, DWCNT-TiO2 hybrid with the DWCNTs of long length showed higher degradation efficiency than that with the short length. (C) 2013 Elsevier Ltd. All rights reserved.