Turbine blades of airplanes and thermoelectric plants work in adverse conditions, with corrosive environment and high temperature and pressure. One way to improve the life or the working temperature of the blades is by the use of special coatings over metallic material applied by Electron Beam – Physical Vapour Deposition (EB-PVD). The most usual material for this application is zirconia doped with yttria. Addition of niobia, as a co-dopant in the Y2O3-ZrO2 system, can reduce the thermal conductivity and improve mechanical properties of the coating. The purpose of this work is to show the influence of the addition of niobia on microstructure of ceramic coating taking in to consideration X-ray diffraction and scanning electron microscopy observations. First result shows a columnar structure with only tetragonal phase in the ceramic coating in the chemical composition range studied.