The photoconvertible surface wettability of TiO2 materials-UV illumination of these materials can generate surfaces that display a 0 degrees contact angle for both water and oily liquids-is investigated, Frictional force. X-ray photoelectron, and Fourier transform infrared spectroscopies are used to supply information at a microscopic level. It is concluded that UV illumination is able to convert initially-hydrophobic TiO2 surfaces into highly amphiphilic ones. This behavior is ascribed to photogenerated Ti3+ defect sires that favor dissociative water adsorption.