Copper oxide films have been sputter deposited on glass substrates by reactive rf magnetron sputtering, using a solid copper target and an argon–oxygen gas atmosphere. The films were characterized by SEM/EDAX, XPS, AFM, profilometry and spectrophotometry. Optical transmission in the prepared films was measured by spectrophotometry in the 400–850 nm wavelength region. The optical transmission was found to increase from below 10% to above 80% as the rf power was reduced from 800 to 200 W at a wavelength of 550 nm. The optical bandgap value also increased from 2.05 to 2.4 eV with a reduction in rf power from 800 to 200 W.