[6,7,8]. Among these, the sol-gel coatings for corrosion protection of metals are considered a promising alternative due to their easy preparation at low temperatures and to the possibility to incorporate various additives and/or nanoparticles in order to control the physical and chemical properties of the coatings [9,10].Layers of oxides such as SiO 2 , ZrO 2 , Al 2 O 3 , TiO 2 , CeO 2 , etc. provide effective protection to metal substrates due to their very good chemical and thermal stability. Among them, SiO 2 layers act very efficiently as corrosion protectors of metals under different temperatures. Moreover, due to the fact that using alkoxysilanes as precursors in the formation of silica solgels the reaction is quite gentle, this approach is extensively used in pretreatment of metal surfaces [6]. It should be emphasized that the introduction of dopants, such as small amounts of nanoparticles (e.g. CeO 2 , ZrO 2 [10] etc.) in the SiO 2 layer could significantly improve the barrier properties of the coatings and, consequently, their corrosion resistance. Moreover, properties of SiO 2 sol-gel coatings and nanoparticles can be influenced by using different surfactants during the preparation process [11].Zinc has found widespread use as the basis of a whole range of sacrificial coatings for ferrous substrates. However, the life span of such coatings is limited due to the aggressive nature of some environments, particularly those containing industrial pollutants. Consequently, efforts are made in order to enhance their service life.In this context, our investigation was focused on the preparation and characterization of different type of porous and compact silica-based protective coatings on zinc and glass substrates by using sol-gel method, in the absence or in the presence of surfactants. The optical and the electrochemical properties of the coatings, as well as the effect of film thickness on its protection ability were also studied.