Noble metals (Ir, Pt) films were prepared by MOCVD using metal-acetylacetonate precursors. The effects of deposition conditions on deposition rates, composition and microstructure were studied, and the optimum conditions were determined. A small amount of oxygen addition to the source gas was effective to prepare high-purity films. Epitaxially grown films were obtained on several kinds of single crystalline substrates. Black-colored powdery films containing impurity carbon were prepared without oxygen addition. These black films consists of fine particles about several nanometer in size. Ir films prepared without oxygen addition showed superior electrical and catalytic properties as an electrode for zirconia solid electrolytes particularly below 600-degrees-C.