The　oxidation-wear　properties　of　WC-Co　cermet　at　high　temperatures　were　remarkably　enhanced　by　Ru　addition　for　increasing　life　expectancy　of　cermet　tools　in　high-speed　cutting　processes.　The　oxidation-resistant　mecha-nisms　of　Co　with　substitutional　Ru　were　disclosed　by　calculating　the　energy　barrier　for　oxygen　adsorption　and　diffusion　in　Co　with　and　without　Ru　doping.　Particularly,　the　oxidation　of　WC　was　effectively　inhibited　due　to　the　suppression　of　reactions　between　cobalt　oxides　and　WO3.　Thus　less　cracking　occurred　in　the　Ru-containing　cermet　as　its　tribolayer　contained　fewer　oxides　with　low　shear　resistance,　which　in　turn　protected　the　subsur-face　materials　from　further　oxidation.