Аннотация:New copper-containing organosilicon hybrid materials were synthesized by the reaction of branched polymethylsilsesquioxane with copper nanoparticles prepared by the metal-vapor synthesis. Hybrid materials showed a high activity in the catalytic olefination of p-chlorobenzaldehyde hydrazone with polyhaloalkanes such as CBrCl3, CBr4 and CF3CBr3 to afford the corresponding halostyrenes in the yields above 80%. The structure and composition of the prepared nanocomposites were studied by X-ray usingsynchrotron radiation to show that the active sites of the catalysts are mixed copper(i)–copper(ii) oxides (Cu–Cu2O–CuO) in nature.