The electrochemical-chemical (EC), electrochemical, chemical, electrochemical (ECE), and electrochemical, chemical, electrochemical-electrochemical, chemical, electrochemical (ECE-ECE) models with and without an included α variability were applied to the reduction of 2-methyl-2-nitropropane, benzenesulfonyl fluoride, and p-toluenesulfonyl fluoride. The three cases where a variability may occur are noted and discussed. It is shown that a variability, if present, may be of importance for ECE sequence in relation to k f determination.The presented cyclic voltammetry data obtained on glassy carbon electrode in the wide scan rate region were fully suitable for determination of kinetic parameters by estimation.