Titanium　dioxide　with　CoB　amorphous　alloys　nanoparticles　deposited　on　the　surface　is　known　to　exhibit　higher　catalytic　activity　than　the　CoB　amorphous.　A　study　of　the　structure　of　such　system　is　necessary　to　understand　this　effect.　A　quantum　chemical　study　of　Co2B2　on　the　TiO2　(110)　surface　was　studied　using　periodic　slab　model　within　the　framework　of　density　functional　theory　(DFT).　The　results　of　geometry　optimization　indicated　that　the　most　stable　model　of　adsorption　was　Co2B2　cluster　adsorbed　on　the　hollow　site　of　TiO2.　The　adsorption　energy　calculated　for　Co2B2　on　the　hollow　site　was　439.3　kJ/mol.　The　adsorption　of　CO　and　O2　was　further　studied　and　the　results　indicated　that　CO　and　O2　are　preferred　to　adsorb　on　the　Co2　site.　Co-adsorption　of　CO　and　O2　shows　that　Co2B2/TiO2　is　a　good　catalyst　for　the　oxidation　of　CO　to　carbon　dioxide　in　the　presence　of　oxygen.　Copyright　©　2010,　Dalian　Institute　of　Chemical　Physics,　Chinese　Academy　of　Sciences.