Investigations of the properties of supported nano-scale Au catalysts in the partial oxidation of three different polyvalent oxygen substituted compounds are presented. The relations between Au particle size and catalytic properties of Au/Al2O3 in the partial oxidation of ethylene glycol to glycolic acid as model reaction are discussed. Moreover, influences of the nature of the alumina support and the applied precipitation agent on the catalyst properties were studied. Furthermore, the potential of these catalysts for the industrial interesting partial oxidation of glyoxal to glyoxylic acid was checked. However, it seems that the oxidation of glyoxal is dominated by a C-C rupture leading to formic acid, mainly. Finally, the excellent selectivity of gold supported on alumina or titania in the partial oxidation of aldehyde groups of saccharides to carboxylic groups is briefly presented. (C) 2004 Elsevier B.V. All rights reserved.