The main aim of this research is the study of electrochemical oscillations in current by means of recurrence plots at different potentials in which products of corrosion are formed, originating pitting corrosion of copper in different saline solutions containing chlorides and sulphates. The dynamics of the formation of corrosion products was characterized by determining if the passive layer is adequate or not to give origin to the pitting corrosion phenomenon. A key contribution of this work to the study of corrosion is the fact that it was found that pitting corrosion begins at the quasi-periodic oscillation potential and not at the so-called pitting potential, which in this work will be denominated apparent pitting potential. This has been proved by means of SEM micrographs at the quasi-periodic potential and with the aid of electrochemical oscillation measurements and qualitative and quantitative recurrence analysis of electrochemical oscillation time series. (C) 2005 Elsevier B.V. All rights reserved.