Abstract Experiments were performed whereby steel specimens in natural sea water were successively cathodically polarized, depolarized or partially depolarized, and then repolarized to simulate the life cycle and retrofit of a galvanic cathodic protection (cp) system on space-frame type offshore structures. Emphasis was placed upon the current density required for repolarization because of importance of this parameter in design of cp retrofit systems. Relationships were established between the steady-state current density during the initial and partial depolarization periods and the current density demand for repolarization.