Recent studies of the CO oxidation activity exhibited by highly dispersed nano-gold (Au) catalysts have reached the following conclusions: (a) bilayer structures of Au are critical; (b) a strong interaction between An and the support leads to wetting and electronrich An; (c) oxidative environments deactivate An catalyst by re-oxidizing the support, which causes the An to de-wet and sinter. Recent results have shown that the direct intervention of the support is not necessary to facilitate the CO oxidation reaction; therefore, an Au-only mechanism is sufficient to explain the reaction kinetics. (c) 2005 Published by Elsevier B.V.