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This work presents the study of the corrosion-electrochemical behavior of titanium alloy Grade 2 treated with combined coatings—presaturation with nitrogen diffusion layer by thermal-chemical treatment, oxygen diffusion layer by thermal-chemical treatment, and a titanium oxynitride (TiN_xO_y) coating deposited by magnetron sputtering—in physiological solution. Structural analysis has shown that TiN_xO_y can be represented as a face-centered cubic (fcc) structure in which nitrogen atoms are replaced by oxygen atoms, or oxygen atoms are replaced by nitrogen atoms. Presaturation of titanium Grade 2 with oxygen and nitrogen leads to the formation of TiN_xO_y with near equiatomic composition at subsequent oxynitriding by magnetron sputtering. Rutherford backscattering spectrometry (RBS) measurements show the homogeneity of the coating composition. The surface of titanium Grade 2 with a nitrogen diffusion layer presents the highest lightness factor and reflectivity in the range of the visible spectrum. Diffusion presaturation of titanium Grade 2 with either oxygen or nitrogen provides better adhesion of TiN_xO_y film to substrate. The presence of an oxygen diffusion layer leads to a stronger bond. It was found that a TiN_xO_y coating increases the corrosion resistance (isotonic solution of 0.9 % sodium chloride (NaCl)) 1.2 times as compared to a nontreated alloy. When the titanium alloy was presaturated with oxygen or nitrogen, the combination of the Physical Vapor Deposition (PVD) oxynitride coating and the diffusion layer, 50µm thick, assists in additional enhancement of corrosion properties 1.5 to 3 times.