A rigorous expression is derived for the scanned deposition potential stripping chronopotentiometry (SSCP) curve for the case of quasi-reversible and irreversible redox reactions. The equation is fully applicable to both a conventional (macro) electrode and a microelectrode. SSCP curves are shown to have a spectacular insensitivity to electrochemical irreversibility and this feature is even more pronounced at a microelectrode. These observations can be readily explained by considering the relative location of the curves on the potential axis. Modification of the experimental conditions (deposition time, electrode volume) allows the extent of resistance to irreversibility to be manipulated. These remarkable characteristics have far-reaching implications for in situ analysis, and allow the effects of irreversibility to be easily distinguished from e.g. those of chemical heterogeneity in the metal speciation. (C) 2003 Elsevier B.V. All rights reserved.