The effects of element migration related to cathodic current polarization on the stability of La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF) cathodes are investigated at 750 degrees C for 120 h. The electrochemical results show that performance activation is the characteristic of cathodic current polarization at 200 mA cm(-2) for 120 h on LSCF cathodes. Line profiles of XPS show that cathodic current polarization at 200 mA cm(-2) suppresses Sr surface segregation, which is responsible for the performance activation of LSCF cathodes. Cathodic current polarization also drives Co diffusing from the bulk to the near surface beneath the Sr-enriched layer of LSCF cathodes. The Co migration and change in Co oxidation state are attributed to oxygen vacancies related to Sr surface segregation.