We propose a systematic and mathematically rigorous procedure of performing the expansion or reduction of kinetic models arising in the area of electrochemical transient modelling. The procedure is based on the use of sensitivity analysis and involves calculation of first-order sensitivity coefficients of the transient curves, with respect to the parameters of various candidate or inherent model components (e.g. rate constants of elementary reactions in the reaction mechanisms). By confronting the sensitivity coefficients with the deviations of simulated transients from experimental curves, decisions can be taken as to whether a particular model component should be added to or removed from the model. The utility of this procedure is verified by its application to selected cyclic voltammetric data for two example electrochemical problems : anodic oxidation of 2, 2＇, 3, 3＇,4, 4＇, 5, 5＇-octamethyl-1,1＇-bipyrrole in dichloromethane at a Pt stationary disk electrode (model expansion from E-rev to ErevCirr and cathodic reduction of bis([2(2)] paracyclophane) Ru(II) bis(tetrafluoroborate) in propylene carbonate at a glassy carbon stationary disk electrode (model reduction from ErevErev-DISP to ErevErev). The procedure may become part of a wider, largely automated computer-aided strategy of developing kinetic models in electrochemistry.