Phosphate-containing silica-supported silver and copper catalysts prepared by impregnation method were investigated using TEM, H-2 TPR and CO TPR methods and tested in the reaction of selective ethylene glycol oxidation into glyoxal. It was shown that reversible oxidation-reduction of the active component took place in case of Ag- and Cu-containing catalysts. In case of Cu-containing systems formation of copper oxides on the catalyst surface led to the decrease in catalytic activity. Silver oxide-like species did not form in the presence of phosphate modifier on the surface of Ag-containing systems, and that led to the increase in glyoxal selectivity during ethylene glycol oxidation. (C) 2012 Elsevier B. V. All rights reserved.