The course of electrochemical and chemical oxidation of quaternized pyridyl dihydropyridines has been compared. The splitting off of the carboxylato group from the betaine structure as the substituent in position 4 of 1,4-dihydropyridine ring seems to be the decisive factor in the intramolecular cycloaddition forming indolizines during oxidation. The mechanisms of the electrochemical oxidation in acetonitrile of both tetrahydro-and dihydroindolizines have been studied using rrde voltammetry.