The　development　of　economical,　highly　active,　and　robust　electrocatalysts　for　oxygen　evolution　reaction　(OER)　is　one　of　the　major　obstacles　for　producing　affordable　water　splitting　systems　and　metal-air　batteries.　Herein,　it　is　reported　that　the　subnanometric　CoOx　clusters　with　high　oxidation　state　substitutionally　dispersed　in　the　lattice　of　rutile　TiO2　support　(Co-TiO2)　can　be　prepared　by　a　thermally　induced　phase　segregation　process.　Owing　to　the　strong　interaction　of　CoOx　clusters　and　TiO2　support,　Co-TiO2　exhibits　both　excellent　intrinsic　activity　and　durability　for　OER.　The　turnover　frequency　of　Co-TiO2　is　up　to　3.250　s−1　at　overpotentials　of　350　mV;　this　value　is　one　of　the　highest　in　terms　of　OER　performance　among　the　current　Co-based　active　materials　under　similar　testing　conditions;　moreover,　the　OER　current　density　loss　is　only　6.5%　at　a　constant　overpotential　of　400　mV　for　30 000　s,　which　is　superior　to　the　benchmark　Co3O4　and　RuO2　catalysts.　Mechanism　analysis　demonstrates　that　charge　transfer　occurs　between　Co　sites　and　their　neighboring　Ti　atoms,　triggering　the　efficient　Co-Ti　cooperative　catalytic　centers,　in　which　OH*　and　O*　are　preferred　to　be　adsorbed　on　the　bridging　sites　of　Co　and　Ti　with　favorable　adsorption　energy,　inducing　a　lower　energy　barrier　for　O2　generation.　©　2020　Wiley-VCH　GmbH