Dense, high-index, and reproducible scandium oxide (ScO) thin films with high mechanical strength were grown on glass substrates by metalorganic chemical-vapor deposition. The influence of deposition temperature on the microstructure evolution and optical properties of ScO thin films was investigated by x-ray diffraction, scanning electron microscopy, atomic-force microscopy, transmission electron microscopy, and spectrophotometry. A close relationship between microstructure and optical properties was found for ScO thin films prepared at different deposition temperatures. © 2001 American Institute of Physics.