Using metal beta-diketonate precursors, pure CeO2 and yttria doped CeO2 thin films were prepared on different substrates by MOCVD process. The thin films were polycrystalline in the thickness about 2 mu m, having the fee fluorite structure. The sizes of crystallite estimated from XRD patterns using Scherrer equation were in the range of 50-80 nm. The Ce/Y ratio in the doped CeO2 thin films was 3.3.1, very close to that in the solid mixed precursor. XPS studies revealed that no carbon impurity is incorporated into the thin films. As-prepared doped CeO2 layers on porous support were promising material for electrolyte and electrode in many electrochemistry process.