Mesoporous TiO2 materials with various pore-size distributions were synthesized by using diblock copolymers via a sol-gel process in aqueous solution. The properties of these materials were characterized by FE-SEM, HR-TEM, XRD, DRS, BET, and BJH analysis. All particles have spherical morphology with a diameter range of 1-3 mu m. The mesoporous TiO2 materials calcined at 400 degrees C were found to have different specific surface areas-186, 2 10, and 192 m(2) g(-1) -and average pore sizes depending on the type of diblock copolymer-5.1, 6.1, and 6.4 nm-and their crystallite sizes were found to be 8.1, 8.3, and 8.8 nm. The photocatalytic activity of each sample was investigated by measuring the photodecomposition of methylene blue (MB), and the small crystallite size, large surface area, and small pore size were found to exhibit better photocatalytic activities. In addition, the photocatalytic activities of all the mesoporous TiO2 materials were found to be better than that of commercial TiO2. (C) 2007 Elsevier Inc. All rights reserved.