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　H-2　and　for　preferential　CO　oxidation　in　the　presence　of　H-2,　as　compared　to　the　Pt/Co　bimetallic　component　catalyst　(Pt/Co/TiO2)　prepared　by　H-2　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.　(c)　2010　Elsevier　B.V.　All　rights　reserved.