The oxidation chemistry of indole-2-carboxylic acid has been investigated in phosphate containing supporting electrolytes in the pH range 1.4-9.8 at a pyrolytic graphite electrode by voltammetric studies, spectral studies, controlled potential electrolysis and related techniques. The kinetics of decay of the UV-absorbing intermediate generated during electrooxidation was followed spectrophotometrically and the decay occurred in a pseudo-first-order reaction. The products of the electrode reaction were characterized as 2,4-, 2,6- and 2,7-dioxindoles, C-O-C-and C-C-linked dimers by using GC-MS, IR and H-1 NMR. A detailed interpretation of the redox mechanism of indole-2-carboxylic acid in neutral aqueous medium has been presented to account for the formation of various products. (C) 2004 Elsevier Ltd. All rights reserved.