The standard rate constant of a simple electrode reaction Ox+ne(-)<-> Red, in which both Ox and Red are solution soluble, can be determined by the variation of frequency in the square-wave voltammetry with inverted scan direction: log k(s) = log f(0)(1/2) + log D-1/2 -0.60 +/-0.01. In this equation log f(0) is the abscissa of the intersection of straight lines E-p,E-2 = a log f + b and E-p,E-2 = 0, where E-p,E-2 is the potential of the second peak of the net response, EO is the standard potential, a = 2.3RT/2(1-alpha)nF, b = E-0 - 2a log k(s) + a log D - 0.0353/(1-alpha)n and D is a common diffusion coefficient. (C) 2009 Elsevier Ltd. All rights reserved.