New type of Ag-containing nanostructured catalyst for high-temperature alcohol oxidation was developed on the basis of mesoporous SiO2 support. Active component (silver clusters/nanoparticles) stabilized by support surface and polyphosphate inside the pores. It was shown that Ag/P2O5/SiO2 catalyst provides high activity in the course of ethylene glycol oxidation to glyoxal at 500-600 °C. Formation of stable structure of catalyst during thermal treatment includes self-organization of mesoporous structure and chemical bonding of phosphate with silica. The catalyst treatment in red-ox conditions leads to reversible oxidation-reduction of silver and its redistribution from bulk to surface of the catalyst. Silver nanoparticles stabilized with silica-phosphate support are active species in the ethylene glycol oxidation into glyoxal.