Abstract
The anodic oxidation of copper in hydroxide solutions has been reexamined with the rotating ring and split‐ring disk techniques. A soluble Cu(III) species has been identified in the anodic region at the onset of oxygen evolution. This species has also been generated at gold rings from disk‐produced Cu(II). Passivation processes in the copper (I) and (II) oxidation regions have been analyzed by means of the corresponding ring currents.