Exfoliated graphite oxide (EGO) is prepared by oxidizing exfoliated graphite (EG) using a mixture of KMnO4/H2SO4. The physicochemical characterization of the EGO has been carried out using FT-Raman, FT-IR, XPS, NMR, and diffraction techniques. Colloidal form of EGO is subsequently prepared by ultrasonicating EGO in water. Thin films of EGO on a glassy carbon/gold surface are formed and the electrochemical and ion exchange properties have been studied using various redox systems such as K-4[Fe(CN)(6)], ascorbic acid, and dopamine. The charge-based adsorption properties can be made use of, to either suppress or catalyze ascorbic acid oxidation. Adsorption and preconcentration of dopamine on the EGO film has been shown to electrocatalyze the oxidation of NADH. (C) 2003 Elsevier Inc. All rights reserved.