Repassivation kinetics of wear scars on AISI 304 stainless steel immersed in sodium chloride and sodium phosphate solutions are studied by electrochemical noise and potentiostatic techniques. The classical high-field ion conduction model is used to quantify the repassivation kinetics of tribo-activated stainless steel surfaces under potentiostatic conditions. A modified ion conduction model is proposed to quantify the repassivation kinetics at open-circuit potential. This model provides a unique approach to investigate potential and current transients with charge density in freshly generated wear scars, and to derive the parameters of the repassivation kinetics of wear scars. (C) 2004 The Electrochemical Society.