tIn this study, the time-dependent corrosion protection ability of 10–15 m thin polydimethylsiloxane-nanoparticle composite coatings was evaluated using mainly open circuit potential and electrochemicalimpedance spectroscopy measurements. The best result was obtained for the coating containing 20 wt%hydrophobic silica nanoparticles, where it was possible to achieve protection for almost 80 days in 3 wt%NaCl solution. The protective properties offered by this coating are suggested to be due to a synergisticeffect of the hydrophobicity of the polydimethylsiloxane matrix and the prolonged diffusion path causedby addition of hydrophobic silica particles.