A　Pt　and　Co-B　bicomponent　catalyst　supported　on　TiO2　(Pt/Co-B/TiO2)　is　prepared　by　a　two-step　impregnation-reduction　method.　This　Pt/Co-B/TiO2　catalyst　exhibits　a　higher　activity　for　CO　oxidation　in　the　absence　of　H2　and　for　preferential　CO　oxidation　in　the　presence　of　H2,　as　compared　to　the　Pt/Co　bimetallic　component　catalyst　(Pt/Co/TiO2)　prepared　by　H2　reduction.　Based　on　the　results　of　the　X-ray　photoelectron　spectroscopy　analysis,　the　CO　adsorption　over　different　catalysts　and　the　density　functional　computation　of　Co-B,　it　is　proposed　that　the　electron　transfer　from　B　to　Co　atoms　in　Co-B　with　an　amorphous　structure　may　be　responsible　for　the　promoted　oxidation　of　CO　over　Pt/Co-B/TiO2.　This　electron　transfer　can　keep　a　high　surface　electron　density　of　Pt　in　Pt/Co-B/TiO2　via　inhibiting　the　electron　transfer　from　Pt　to　Co　atoms,　which　is　favorable　for　the　activation　of　CO　species　adsorbed　at　Pt　surface.　©　2010　Elsevier　B.V.