Corrosion of marine constructions and vessels is a very important issue in relation to the safety aspects. It is connected with the fact that many marine constructions are exposed to the aggressive corrosion environment. As a result it leads to vessels collisions and unexpected accidents. The following paper presents the application of dynamic electrochemical impedance spectroscopy (DEIS) for the examination of the initiation stage of stress corrosion fracking (SCC) of aluminum A91050 immersed in 0.1M NaCl solution at room temperature. This paper presents instantaneous impedance spectra obtained at different potential values. The results obtained indicate that the process of the passive layer cracking can be considered as the initiation stage of the SCC and depends on tensile stresses, whereas further evolution of corrosion processes depends on electrochemical conditions.