I-doping TiO2 nanocrystalline powders were synthesised by a simple co-precipitation method. After heat treatment at 500 degrees C, an anatase crystalline phase has been stabilised. The structural and optical properties of the nanostructured powders were investigated by X-ray diffraction, Raman and UV-vis spectrometry. With an increase of the iodine dopant quantity the crystallites size tends to decrease and there is an increase in the structure deformation. A decrease of the energy band gap was observed with an increase of the iodine amount. An increase of the photocatalytic activity of the I-doped TiO2 nanostructured powders with the increase of the iodine content was also observed due to the decrease of the energy bad gap. (C) 2012 Elsevier B.V. All rights reserved.