In the study described in this paper we deposited gold, silver and copper on c-Al 2 O 3 as nanoparticles (<4 nm) and investigated the behavior of these nanoparticles in the preferential oxidation of CO in presence of H 2 . In addition, the effect of addition of CeO x and/or Li 2 O was investigated. All the three metals show preferential oxidation of CO at low temperatures. The oxides added to Au/c-Al 2 O 3 , Ag/c-Al 2 O 3 and Cu/c-Al 2 O 3 improve the catalytic performance of the gold, silver and copper. Interesting and synergistic effects were observed when both the CeO x and Li 2 O were added. Possible mechanisms are proposed.