Dynamic electrochemical impedance spectroscopy (DEIS) has been applied for detailed analysis of the passive-active transient region during the passive layer cracking process. The effect of applied potential and tensile stresses on the passive layer rupture of type 304L stainless steel (SS) immersed in 0.5 M MCI solution at room temperature was examined. This paper presents instantaneous impedance spectra obtained for 304L stainless steel samples at the different potential values that refer to the transition from passive into active state while crack of the passive layer took place. Besides, differential dependencies of electrochemical parameters versus relative elongation have been presented to illustrate the system's dynamics changes. (C) 2004 Elsevier Ltd. All rights reserved.