Copper nanoparticles via chemical reduction of copper sulfate by sodium borohydride in the presence of sodium oleate stabilizing agent have been synthesized and stabilized. X-ray phase analysis has shown that the synthesized nanoparticles in the core consist of metal nanoparticles and the surface is covered with a shell of copper oxide. SEM analysis of nanoparticles stabilized in the presence of sodium oleate showed that copper nanoparticles, coated with the shell of copper oxide, have a narrow particle size range of 14-25 nm. Polymer nanocomposites based on PP/Cu-CuO were obtained by the combining of ex-situ casting solution and hot pressing methods. The structure and electrophysical properties of polymer nanocomposites were investigated. Have been established that at lower concentrations, nanoparticles play the role of structurant, as a result the new polar groups and stable charge-trappings are created in the obtained nanocomposites, which in turn increases the value of dielectric permittivity of nanocomposites and enhances the polarizability of these materials.