The diffusion coefficients of 2,2,6,6-tetramethyl-4-hydroxypiperidin-1-oxyl (I) and 2,2,6,6-tetramethylpiperidin-1-oxyl (II) were determine by chronocoulometric methods. Using cyclic voltammetric and potential step methods, the transfer coefficients and the standard rate constants for the one-electron oxidation electrode reactions of I and II were also measured. In strong alkaline medium (pH 12), the cyclic voltammetric results showed that the relation between the oxidation current of II and the scan rate is consistent with the theor. curve of the catalytic electrode reaction. The catalytic electrode reaction rate constant of II was determine to be 6.3 ?10-1 dm3 mol-1 s-1 by the potential step method.

Key words: OXIDATION, OXYGEN, REACTION KINETICS, NITROGEN, DIFFUSION COEFFICIENTS, FREE RADICAL, REACTION RATE CONSTANT, CHRONOPOTONTIOMETRY, ELECTROCHEMISTRY, ELECTRODE POTENTIAL