Surface　reactive　oxygen　species　play　a　fundamental　role　in　selective　oxidation　and　combustion　reactions　catalyzed　by　metal　oxides.　Unravelling　the　nature　of　these　transient　species,　and　understanding　the　details　of　both　their　electronic　structure　and　reactivity　has　been　for　decades　one　of　the　prime　research　areas　of　surface　and　catalytic　chemistry.　The　longstanding　activity　of　Michel　Che　in　this　area　has　been　a　source　of　inspiration　for　generation　of　researchers,　and　constitute　his　outstanding　and　enduring　scien-tific　legacy.　Present　review　provides　a　survey　of　the　surface　oxygen　species　on　oxide　materials,　which　moving　on　from　the　Che＇s　pioneering　works　includes　noteworthy　results　obtained　during　the　years　by　other　researchers.　In　particular,　applications　of　two　powerful　techniques　such　as　electron　paramagnetic　resonance　(EPR)　and　photoluminescence　(PL)　for　detailed　characterization　of　paramagnetic　(O-,　O-2,　O-3)　and　diamagnetic　surface　oxygen　varieties　(O-surf(2)),　respectively,　are　addressed　here.　Classification　and　insights　into　the　formation　pathways　of　these　species　on　various　oxide　surfaces,　as　well　as　their　involvement　in　model　and　real　gas/solid　and　liquid/solid　reactions　of　catalytic　and　photocatalytic　relevance　is　also　con-sidered.　Finally,　the　relationship　between　the　thermodynamic　and　kinetic　Bronsted　basicity　of　low　coordi-nated　O-2(Lc)　anions　is　discussed,　on　the　basis　of　Che＇s　fundamental　studies　and　on　recent　developments.　(C)　2020　Elsevier　Inc.　All　rights　reserved.