Here, we report a novel synthesis of hollow TiO2 structures via hydrolysis of surfactant-free NH4TiOF3 crystals that were self-assembled at room temperature on a solid substrate from an aqueous solution containing (NH4)(2)TiF6 and H3BO3. The prepared TiO2 film showed highly active and robust photocatalytic behavior for the degradation of organic compounds after heat-treatment at 45 degrees C in ambient air.