Communication: Electrodeposition as an approach to quantum confinement is the idea behind the work on nanocomposite films of Cu and Cu2O reported here. The phase of the film electrodeposited from an alkaline aqueous solution of copper(II) lactate depends on the cathodic current density used, varying from pure Cu2O (a p-type semiconductor) to 98 mol-% Cu, the color of the film changing correspondingly; the electrode potential oscillates spontaneously at fixed current density. It is shown that the Cu2O crystallites exhibit the optical properties of quantum dots.