The aim of this research was to improve corrosion behavior of 7075 Al alloy. Plasma electrolytic oxidation method was employed for this purpose. The coating process was carried out in a silicate base electrolyte using a DC regime with a constant coulomb. X-ray diffractometery (XRD) and scanning electron microscopy was used to evaluate the phase and morphological structure of the coatings, respectively. The results revealed that applying PEO on 7075 Al alloy leads to the formation of a ?-Alumina film, which has a porous surface; and some pores are distributed in its structure. Corrosion behavior of the samples was evaluated after 1 hour immersion in 1M H 2 SO 4 by electrochemical tests. Tafel polarization test showed that the coatings decreased the corrosion current density about 2-10 times, and increase the charge transfer resistance about 2-25 times. Electrochemical impedance spectroscopy (EIS) revealed that that the coatings were formed a physical barrier against charge transfer, and decreased the diffusion of corrosive solution through the coating due to its non-columnar structure. The research was continued by adding different concentration of TiO 2 nanopowders in the electrolyte in order to produce composite coatings. The results revealed that the nanoparticles, irrespective to their concentration, were embed in the coatings, and decreased the coating porosity. The composite coating elemental map showed that TiO 2 nanoparticles were mostly placed in the upper parts of the coatings. X-ray diffractometery method revealed that ?-Alumina is present in the composite coatings phase structure. The composite coatings showed better corrosion and mechanical properties than PEO coatings due to their lower porosity content. Keywords : 7075 Al alloy, Coating, Plasma electrolytic oxidation, Composite coating, Corrosion