Conducting thin films on RuO2were deposited on glass by metalorganic chemical vapor deposition using tris‐trifluoroacetylacetonate‐ruthenium (III) [Ru(tfa)3] as precursor. Smooth, specular, and well adherent films were grown at temperatures as low as 400 °C, if the reaction gas contained water. RuO2was the only phase detected by x‐ray diffraction. The films were investigated by spectroscopic ellipsometry in the energy range of 1.5 to 5.0 eV. Thereby, the real (&Vegr;1) and imaginary (&Vegr;2) parts of the dielectric function were determined at room temperature. The optical constants could be described by three harmonic oscillators in combination with a Drude term for free‐charge carriers. ©1995 American Institute of Physics.