Electrochemical, quantum-chemical and antioxidant properties of antipyrine and its derivatives have been investigated in this work. New quantum-chemical parameter such as difference of formation heats of a molecule and its cation radical (delta deltaH(cat)) has been used in order to describe properties of the investigated substances. Electrochemical properties (oxidation, reduction potentials) have been investigated. Correlation between the calculated delta deltaH(cat) and the experimentally obtained oxidation potentials for antipyrine and its derivatives has been found.