Abstract: A theoretical and experimental investigation of quasi-reversible electrode processes using square wave voltammetry, especially with cyclic voltammetry, is described. The mathematical expressions of current functions have been deduced. It is shown that the difference between the peak potentials for forward sweep and for reverse sweep, ΔEp, is not equal to zero, but increases with decrease of the degree of the reversibility and strongly depends on the standard rate constant, Ks, of the electrode reaction and the voltage scan rate, and it is also independent of the square wave amplitude. With a new parameter proposed, Kc, which is related to Ks and ΔE/τ, one can get the theoretical plot of Ke against ΔEp. Thus, the value of Ks can be estimated from ΔEp measured by cyclic square wave voltammetry and Kc obtained from the theoretical curve. The method has been used to determine the Ks of [Fe(CN)₆]^-3-H₂SO₄ system at glassy carton electrode. The Ks obtained then has a value of 2.5×10^-3cm/s, whichis in fair agreement with 2.1×10^-3cm/s obtained by staircase scan technique and 2.2×10^-3 cm/s as repoprted in literature.

Key words: Cyclic square wave voltammetry, Electrode process, Mathematic method, Theory