The behavior of copper electrodes scratched under potential control in aqueous electrolytes is presented. In alkaline solution the metal surface shows the presence of two distinct types of oxidized monolayer, ascribed to and , each formed over a unique potential range well below the reversible potential for bulk formation. The monolayer is a necessary precursor to passivation of the metal, and in sulfuric acid solution only the monolayer is observed. This monolayer acts as an intermediate laver in both the dissolution and passivation processes and probably also exists during steady‐state hydrogen evolution. Addition of ammonia to alkaline electrolytes modifies the monolayer, probably by incorporation of , rendering formation of more difficult.