To date, simple and operative electrochemical methods are widely used to study antioxidant properties of various biological objects. One of them is the amperometric method, which is used in various fields of science, technology and medicine to determine the antioxidant activity (AOA) of various beverages, extracts and biological fluids, as well as the total content of antioxidants (AOs) present in them. Measurements of AOA (electrochemical oxidability) of some known individual AO and their mixtures by the amperometric method was performed in the present work. The coefficients of their oxidability were determined. The AOA values obtained correlate well with the AOA of these compounds measured by other methods. The coincidence of the experimental values of AOA and the values calculated with... the use of the coefficients of oxidability for each component of the mixture was observed for most combinations of binary mixtures of used AOs. This indicates the absence of interaction between them (synergism or antagonism) during the oxidation. Several mixtures with a lower value of the measured AOA compared with the calculated value (antagonism) represented the exception. During the electrochemical oxidation of the “oxidized glutathione + ascorbic acid” mixture, partial reduction of glutathione by ascorbic acid is likely to proceed, which results in an excess of the measured AOA value over the calculated value. The results obtained may be useful when working with devices based on the amperometric method.