The mesoporous anatase TiO2 nanoparticles with great surface areas were prepared using iodine ion as dopant by sal-gel method. The as-prepared samples were characterized by differential thermal analysis, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller, and UV-visible diffuse reflectance spectroscopy. The photocatalytic activity of the as-prepared samples was evaluated through photocatalytic decolorization of methylene blue aqueous solution. The above results of the characterization test not only indicate that iodine ion can inhibit the collapse of mesoporous channels resulting from the overquick dehydration among the free hydroxyl groups and plays a part in structure-directing, but also the calcination temperature has a crucial effect on the mesoporous structure and the amount of iodine doped in TiO2. The BET surface area of the as-prepared mesoporous TiO2 (208.98 m(2) g(-1)) calcinated at 300 degrees C is 4 times larger than that of the pure TiO2 (50.37 m(2) g(-1)). The catalyst doped with 13.2%(mole ratio) I and calcinated at 300 degrees C has the best performance. The efficiency of photocatalysis for MB is greatly improved with TiO2 doped by iodine ion under UV and visible light irradiation. (C) 2011 Elsevier B.V. All rights reserved.