Incident energy, fluence of helium ion and temperature for blister formation in rutile TiO 2 (100) films were investigated. Epitaxial rutile TiO 2 (100) films were grown on α-Al 2 O 3 (0001) substrates by pulsed laser deposition. The films were irradiated at room temperature and 95K with 4keV helium ions up to fluence range from 1.0×10 16 to 2.3×10 17 ions/cm 2 . The surface morphology of TiO 2 films was observed by scanning electron microscope and atomic force microscope. Rutherford backscattering spectroscopy with channeling was used to determine the depth profile of radiation-induced damage. In the case of room temperature irradiation with fluences higher than 2×10 16 ions/cm 2 , helium blisters with 100–200nm sizes in TiO 2 films were observed. Furthermore, helium irradiation at 95K resulted in smaller size blisters (∼50nm). It is suggested that the size of blisters in TiO 2 (100) films is strongly affected by the temperature during the helium irradiation. The photo-induced superhydrophilicity of TiO 2 films was improved by high fluence helium irradiation, which caused blister growth.