An active corrosion protection circuit for a brake disc-pad unit of a motor vehicle includes one of a metal disc and a pad adapted to selectively block the disc. A direct electric voltage source and an electric conductor connectable to the electric voltage source and one of the disc and the pad forms an electric circuit causing a monopolar current flux between the disc and the pad when the pad blocks the disc so that the action of the current is localized in a contact zone between the disc and the pad.