Аннотация:Polythermic decomposition (PD) of Co(COO)2.2H2O synthesized within pores of photonic crystals based on SiO2 was studied by thermogravimetry and differetialscanning calorimetry techniques in He and air in flow and under static conditions. PD results in the CoO and Co3O4 formation. The CoO and Co3O4 nanoparticles formed exhibit high catalytic activity in CO oxidation by oxygen both in air and in He.