Mesoporous TiO2 microspheres have been made on a large scale by a simple hydrothermal method without using any surfactants or templates. The products were characterized by XRD, SEM. TEM, SAED, nitrogen adsorption, and UV-vis spectroscopy. Results indicate that the TiO2 microspheres, with a diameter of 0.8-1.2 mu m, are composed of numerous TiO2 nanocrystals with an average diameter of 5.6 nm. The average pore size, BET surface area, and optical band-gap energy of the microspheres are 4.0 nm. 185.6 m(2)/g, and 3.42 eV. respectively.