The　catalytic　oxidation　of　CO　toward　CO2　on　ruthenium-embedded　hexagonal　boron　nitride　nanosheet　(h-BN)　was　studied　by　periodic　first-principle　methods.　The　calculation　results　indicate　that　this　catalyst　is　extremely　stable　and　the　adsorbed　oxygen　species　can　be　efficiently　activated　by　the　embedded　metal　atom.　Two　reaction　pathways　of　the　CO　oxidation　were　considered　in　detail:　the　Langmuir-Hinshelwood　(LH)　and　the　Eley-Rideal　(ER)　pathways.　As　a　result,　the　CO　oxidation　process　would　like　to　firstly　take　place　following　ER　mechanism　to　produce　CO2　plus　an　atomic　O　and　then　a　second　CO　reacts　with　the　remanent　oxygen　atom　to　form　CO2　through　LH　pathway.　The　calculated　energy　barriers　for　these　two　reaction　steps　are　as　low　as　0.42　and　0.37　eV,　respectively,　indicating　its　application　at　low　temperatures.　This　study　can　be　expected　to　provide　useful　information　for　the　development　of　highly　active　catalyst　for　CO　oxidation.　(C)　2013　Elsevier　B.V.　All　rights　reserved.