Mesoporous TiO2 has been synthesized by the sol-gel method, using a nonionic triblock copolymer P123 as surfactant template under acidic conditions. The as-prepared samples were characterized by thermogravimetry- differential thermal analysis (TG-DTA), nitrogen absorption-desorption (BET), field emission scanning electron microscopy, and transmission electron microscopy. The photocatalytic activity of the mesoporous TiO2 was evaluated by degradation of methylene blue under high-intensity UV light irradiation; the amount of methylene blue was measured by UV-visible spectroscopy. TG-DTA analysis revealed that the surfactant had been removed partly in as-synthesized samples. BET analysis proved that all the samples retained mesoporosity with a narrow pore-size distribution (4.5-6.3 nm) and high surface area (103-200 m2/g). All calcined mesoporous TiO2 had high photocatalytic activity in the photodegradation of methylene blue. © 2012 Springer Science+Business Media B.V.