In the present work silica (SiO2) coatings as interlayer and silica-titania (SiO2/TiO2) hybrid coatings as top layers, obtained by the sol-gel method and successfully applied on the polymeric substrate, were investigated as a sealing coatings. Materials were newly obtained and the morphological and structural investigations were performed. The study of chemical structures, using EDS (Energy-dispersive X-ray spectroscopy), XPS (X-ray photoelectron spectroscopy) and Raman spectroscopy, confirmed the presence of particular oxide structures. The surface morphology and topography investigations were carried out using SEM (scanning electron microscopy) and AFM (atomic force microscopy) and indicated the homogeneity of the obtained coatings and smoothing of material surface by applied coatings. The cross-section of the substrate-coating system investigated with TEM (transmission electron microscope) showed the internal structure of coating. Moreover, the permeability test revealed the reduction of the CO2 and H2 permeability and the permeability coefficient for the obtained materials. The results show potential for application of obtained materials as sealing coatings in high pressure hydrogen storage systems.