Ultralong CdO nanowires (NWs) were synthesized on Au coated Si and quartz substrates by using vapor

transport method. The synthesis temperature was chosen via thermal gravimetry analysis (TGA) and it

was 1150C. The formation of CdO was confirmed by energy dispersive analysis of X-ray (EDAX) and Fourier transform infrared (FT-IR) spectroscopy analysis. The CdO nanowires was found to grow via a vapor– solid growth mechanism. The diameters of the nanowires were in the range 30–90 nm and the lengths were greater than 30lm. The optical constants, the thickness and the surface roughness of the prepared CdO NWs films were determined by spectroscopic ellipsometry measurements. A two layers model was used to fit the calculated data to the experimental ellipsometric spectra. The obtained optical constants were compared with those obtained by other preparation methods. The optical band gap was found to be 2.41 eV. An emission peak at550 nm was recorded, which should corresponds to the near band-edge emission of CdO.