Electrolyte layers of Gd2O3-doped CeO2 were synthesized by MOCVD with the use of Ce(tmhd)4 and Gd(tmhd)3 as reactants in the temperature range of 500–800°C at reduced pressure. Ar and air were carrier gases. The layers were deposited on the inner surfaces of quartz glass tubes and flat glass substrates. The obtained layers were non-porous and smooth. The layers synthesized at temperature of 500°C were amorphous. At higher synthesis temperatures, the deposited layers were nanocrystalline. The higher the synthesis temperature, the larger the grains. When the synthesis process was controlled by mass diffusion to the substrate, then a correlation between the chemical composition of reactants and chemical composition of the synthesized layer can be determined. The obtained layers were also examined by scanning electron microscopy, X-ray analysis and UV‐VIS spectroscopy. Additionally, the chemical composition of the synthesized layers was investigated using an EDS analyzer.