In this article, the temperature dependence of the Ti-18Zr-15Nb alloy dilatation in the ultrafine-grained (UFG) state ob-tained by equal-channel angular pressing (ECAP) and coated using the plasma-electrolytic oxidation (PEO) method was investi-gated. The stability of the formed PEO coatings to heating and cooling has also been determined. The results showed that a sharp increase in the thermal expansion coefficient (TEC) in the 350°C temperature range indicates the presence of a phase transfor-mation. During the tests, the porous coating on the Ti-18Zr-15Nb alloy is preserved, but the cracks become more intense and extended