Samarium and nitrogen co-doped titania (Sm/N-TiO2) was successfully prepared via coprecipitation method. The resulting materials were characterized by X-ray diffraction (XRD), N-2 physical adsorption, UV-vis absorbance spectroscopy. X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared (FTIR) spectra. Experimental results indicated that samarium doping inhibited the growth of crystalline size and the transformation from anatase to rutile phase. The photocatalytic activities of the samples were evaluated for degradation of salicylic acid under visible light irradiation. It was found that the Sm/N-TiO2 samples presented much higher photocatalytic activity than N-TiO2 and pure TiO2 under visible light irradiation. This could be attributed to the appropriate crystallite size, more efficient separation of electrons and holes on Sm/N-TiO2. In our experiments, the optimal dopant amount of samarium was 1.5% for the maximum photocatalytic degradation and the sample calcined at 400 degrees C showed the best reactivity. (C) 2010 Elsevier B.V. All rights reserved.