An @[email protected] that is characteristic of a charge-transfer process and the experimental conditions (such as the composition of the solvent and @[email protected] and the temperature) under which it is investigated, and whose nature depends on the technique that is employed. Some typical characteristic potentials are the @[email protected] in @[email protected], the @[email protected] in chronopotentiometry, the @[email protected] and the @[email protected] in linear-sweep voltammetry, and the @[email protected] in ac @[email protected]