The errors of electrode kinetic measurements carried out with the potential and voltage step techniques (for single and double pulsar) are calculated for several graphical and numerical data analysis methods. The following errors are examined : the random, experimental errors caused by the uncertainties of the potential, current, time, electrode area, and ir compensation; and the systematic errors caused by the inadequacies of the mathematical treatments and by the neglect of the slow rise time of a real potentiostatic system. The errors are presented as a function of the reaction resistance and of the rate constant parameter. The latter. which is defined as [R,/(AR, + R,)] (iJvnF)(1/Db'2C, + l/&%,), is equal to 632 k, under simplified conditions. For a maximum tolerable error of + 20 per cent in the determination of the exchange current density, the limitation of the techniques can be summarized as follows, The classical potent&tat&z technique with exact ir compensation can be used to a rate constant parameter of about 200 (k, r 0.3cms-'). The useful range can be extended to about 1000 (k, % 1.5cm 5-l) by using a numerical data evaluation method whii takes into consideration the rise time of the potential. For the voltage step technique and the potentiostatic technique with uncompensated resistance, the limits of applicability can be significantly lower than the above values, depending on the ratio of reaction resistance to total celi resistance. NOMENCLATURE Defined by equation (10) Electrode area (cm') Concentration of species j in the bulk solution (mol cm-') Concentration of species j near the electrode surface (mol cm-3) Diffusion coefficient of species j (cm* s-l) Faraday constant Current density (A cm-*) Apparent exchange current density (Acm-') Current (A) Apparent standard rate constant (cm s-l) Total number of electrons transferred in the overall reaction *The submitted manuscript has been authored by a con-