ESB chief executive Padraig McManus has told the company's board he plans to retire.
Mr McManus, who was appointed to the post in early 2002, will remain in place until a successor is appointed.
His original seven-year contract was later extended by three years. Mr McManus joined ESB in 1973 after graduating in engineering from UCD.
ESB chairman Lochlann Quinn described Mr McManus's period in charge as 'one of exceptional achievement', adding that he had led the company through a period of unprecedented change in the energy business.
