A general solution for any stepped-potential method in the case of the pseudo-first order catalytic process is presented. This solution is valid for a reversible redox reaction at a plane electrode whatever the magnitude of the forward and the backward rate constant of the parallel homogeneous chemical reaction. It is shown that polarography, normal pulse polarography, differential pulse polarography and square wave voltammetry can be analysed easily and uniformly with the aid of dimensionless parameters. For all these methods, a kinetic zone diagram is also presented.