The influence of plasma processing of silica and crystalline silicon substrates on the formation of polymeric layers of PS/PMMA blends by sorption from 50 vol. % concentration toluene solutions was analyzed. The morphology dependence of PS/ PMMA blend films on the type and condition of substrate processing was studied by X-ray photoelectron spectroscopy (XPS), ellipsometry and atomic force microscopy (AFM). It was shown that reduction of carbon and oxygen components from the surface contaminants as well as the existence of a nonstoichiometric SiOx layer on the Si surface contributed to the hydrophilicity of the substrate. These processes can be used to produce thin nanostructured polymer blend films.