Mesoporous titania films have been synthesized by a modified sol-gel method in conjunction with amphiphilic triblock copolymers. The effects of ammonia vapor treatment on the formation of mesoporous structures were investigated. Mesoporous titania films with hexagonal structures were obtained by ammonia vapor treatment. Without ammonia vapor treatment, it was found that the mesoporous structures collapse due to crystallization. The framework of mesoporous titania was found to be amorphous. Mesoporous titania films prepared by ammonia vapor treatment showed thermal stability up to 500 degrees C. Mesoporous samples showed better photo-catalytic activity than anatase titania films under UV-light irradiation.