The　activation　of　H2O　is　a　key　step　of　the　COS　hydrolysis,　which　may　be　tuned　by　oxygen　vacancy　defects　in　the　catalysts.　Herein,　we　have　introduced　Cu　into　Co3O4　to　regulate　the　oxygen　vacancy　defect　content　of　the　catalysts.　In　situ　DRIFTS　and　XPS　spectra　reveal　that　COS　and　H2O　are　adsorbed　and　activated　by　oxygen　vacancy.　The　10　at%　Cu　doped　Co3O4　sample　(10Cu–Co3O4)　exhibits　the　optimal　activity,　100%　of　COS　conversion　at　70　°C.　The　improved　oxygen　vacancies　of　Cu–Co3O4　accelerate　the　activation　of　H2O　to　form　active　–OH.　COS　binds　with　hydroxyl　to　form　the　intermediate　HSCO2−,　and　then　the　activated　–OH　on　the　oxygen　vacancy　reacts　with　HSCO2−　to　form　HCO3−.　Meanwhile,　the　catalyst　exhibits　high　catalytic　stability　because　copper　species　(Cu+/Cu2+)　redox　cycle　mitigate　the　sulfation　of　Co3O4　(Co2+/Co3+).　Our　work　offers　a　promising　approach　for　the　rational　design　of　cobalt-related　catalysts　in　the　highly　efficient　hydrolysis　COS　process.　©　2021　Institute　of　Process　Engineering,　Chinese　Academy　of　Sciences