Cadmium oxide semiconductor films were cathodically electrodeposited on F- doped SnO2 substrates from an aqueous 0.1 M KCl medium containing dissolved Cd2+ species and O-2. The mechanistic aspects of the electrodeposition were briefly explored using cyclic voltammetry in the supporting electrolyte where either Cd2+ or O-2 or both were intentionally omitted. The CdO films were potentiostatically deposited at 80 degrees C followed by a postdeposition thermal anneal at 450 degrees C. These samples were then analyzed by X- ray diffraction, scanning electron microscopy, Auger electron spectroscopy, and UV-visible diffuse reflectance spectrophotometry. The photoelectrochemical behavior of these films is then presented. (c) 2005 The Electrochemical Society.