The developed methods of formation and results of the study of the hydrophobic layers on aluminum alloy, previously subjected to plasma electrolytic oxidation (PEO) and additional treatment (either in ethanol solution or under UV-radiation in the presence of ozone plasma) with subsequent deposition of the hydrophobic agent (methoxy-{3-[(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluoroctyl) oxy] propyl}-silane solution in decane) have been described. It was found, that the formed composite layers possess a hydrophobicity (contact angle higher 157o) and high anticorrosion properties (the impedance modulus, |Z|f=0.01Hz, ranges from 9.2·109 to 4.0·1010 Оhm·cm2 depending on the treatment procedure).