The electrochemical oxidation of the central mammalian alkaloid l-methyl-6-hydroxy-l, 2, 3, 4tetrahydro-@-carboline (1) has been studied in neutral aqueous solution at a pyrolytic graphite electrode (PGE). Voltammograms of 1 show two closely spaced oxidation peaks, I, and 11,. At potentials less positive than the peak potential (E,) for peak I,, 1 is oxidized to a radical intermediate which dimerizes to give two diastereomers of 5, 5'-bi (l-methyl-6- ...