Thin dielectric films of niobium oxide have been deposited on silicon and quartz substrates by pyrolysis of the niobium alcoholate in an oxidizing ambient. Optical measurements have been made on these films in the spectral range 0.2–2.6 µm. Information on dispersion, fundamental absorption edge, and absorption coefficient (as related to photon energy) has been obtained. An electrical evaluation of the films has been made, including dielectric properties and MOS behavior.