Highly　transparent　TiO2　and　TiO2　-based　binary　oxide　thin　films　were　prepared　using　an　ionized　cluster　beam　(ICB)　deposition　method.　The　transparent　TiO2　thin　films　showed　high　photocatalytic　performance　due　to　their　low　scattering　of　incident　light　as　compared　to　TiO2　powders.　As　well,　the　thin　films　showed　high　surface　wettability　under　UV　light　irradiation,　depending　on　the　surface　morphology,　surface　area,　and　crystal　phase.　Then,　we　discussed　the　mechanism　of　the　photoinduced　surface　wettability　changes　using　near-infrared　spectroscopy　and　clarified　that　the　hydrogen　bond　networks　between　H2　O　molecules　on　the　TiO2　surface　lessen　during　UV　light　irradiation.　Furthermore,　the　TiO2　–SiO2　binary　oxide　thin　films　contained　unique　tetrahedral　TiO4　species　incorporated　within　the　SiO2　matrices　but　did　not　show　efficient　photoresponse　in　the　surface　wettability.　In　contrast,　the　TiO2　–B2　O3　thin　films　contained　the　TiO2　nanoclusters　within　the　B2　O3　matrices　and　showed　high　surface　wettability　under　UV　light　irradiation.　Crystalline　TiO2　thin　films　with　an　anatase　structure　were　prepared　on　polycarbonate　substrates　at　100 °C　using　an　radio-frequency-magnetron　sputtering　deposition　method.　The　TiO2　thin　films　showed　high　transparency　and　mechanical　stability　against　scratching　and　bending.　The　TiO2　thin　films　on　polycarbonates　exhibited　photoinduced　surface　wettability　under　UV　light　irradiation　of　0.05−1 mW cm−2.　©　2023　WILEY-VCH　GmbH.