We　studied　the　adsorption　of　CO　molecules　on　perfect　and　Pt-adsorbed　t-ZrO2(101)　surfaces　using　a　periodic　slab　model　by　PW91　of　generalized　gradient　approximation　(GGA)　within　the　framework　of　density　functional　theory.　The　results　indicated　that　the　second　sub-surface　oxygen　and　the　second　bridge　sites　are　the　most　stable　adsorbed　sites　for　CO　and　Pt　on　the　ZrO2(101)　surface,　respectively.　When　the　coverage　is　0.25　ML　(monolayer)　the　most　stable　models　were　obtained　with　adsorption　energies　of　56.2　and　352.7　kJ.mol(-1).　The　most　stable　model　of　CO　adsorbed　on　the　Pt/t-ZrO2(101)　surface　was　obtained　by　C-end　adsorption　with　an　adsorption　energy　of　323.8　kJ　.　mol(-1).　We　considered　vibrational　frequency　calculations,　density　of　states　and　the　Mulliken　population　of　the　adsorption　systems　before　and　after　adsorption　and　these　were　compared　for　CO　and　Pt　adsorption　onto　the　ZrO2　surface.　The　results　indicate　that　the　C　-　O　bond　length　of　0.1161　nm　after　adsorption　at　the　C-end　is　elongated　compared　with　the　0.1141　and　0.1136　nm　of　free　and　adsorbed　on　ZrO2.　The　vibrational　frequency　of　CO　at　2018　cm(-1)　is　red-shifted　compared　with　free　CO.　CO　has　some　positive　charge　after　adsorption　and　charge　transfer　is　predominantly　by　the　pi　back-donation　bonding　mechanism　of　the　Pt　5d　-＞　CO　2　pi　orbital.