The influence of preliminary oxidation and gas nitriding of titanium alloy on the process of plasma electrolytic synthesis of oxide-ceramic coatings was investigated. PEO was carried out in the electrolyte KOH (5 g/l), Na2SiO3(5 g/l). The phase composition, thickness and porosity of the obtained oxide-ceramic coatings were determined. It was shown that after preliminary oxidation the number of pores increases more than 2 times compared to the gas nitriding alloy. Preliminary gas nitriding leads to the formation of plasma discharges of a significantly larger pore size of 1.66 e−12 m2 compared to 7.74 e−13 m2 for the preliminary oxidized alloy. This indicates a significantly higher power of plasma discharges that arise on titanium nitride. These results correlate with the phase composition and thickness of oxide-ceramic coatings. Based on the analysis of X-ray diffraction patterns, it was established that the main phases in the surface layers are titanium oxides: rutile, brookite and anatase. Titanium nitride contributes to the formation of a significantly larger amount of high-temperature titanium oxides rutile and brookite in the PEO process.