The electrochemical oxidation of 1, 3-dimethylxanthine has been studied in the pH range 2.3— 10.3 at a pyrolytic graphite electrode. The conjugate base has been found as the electroactive species oxidized over the entire pH range. The 4e, 4H+ charge transfer step is followed by competitive irreversible chemical reactions. The decomposition of UV-absorbing intermediate generated during the electrooxidation has been found to follow first-order ...