Some biologically important and melatonin-related indole-3-propionamide derivatives were synthesized. The compounds synthesized were analyzed and characterized first by NMR and mass spectrometry and then investigated by analytical voltammetric techniques. Based on this study a simple, rapid and sensitive voltammetric method was developed for the determination of the indole derivatives that are readily oxidized at the carbon-based electrodes. The oxidative behavior of the indole derivatives was studied as a function of pH at a glassy carbon electrode. The characteristics of the corresponding electrode reaction were discussed. (C) 2001 Elsevier Science S.A. All rights reserved.