Self-assembled mesoporous TiO 2 thin films have been synthesized by sol-gel method using amphiphilic triblock copolymer as a template under acidic conditions. The samples were characterized by small angle X-ray diffractometry (SAXRD), thermogravimetry-differential thermal analysis (TG-DTA), transmission electron microscopy (TEM), N 2 adsorption and field emission scanning electron microscopy (FE-SEM). The structural characteristic of mesoporous TiO 2 thin films strongly depends on the pH values of precursor solution, heat treatment conditions, and the condensation of templates. It has been proven that the framework of obtained films consisted of TiO 2 nanocrystallites.