Graphite-castor oil polyurethane composite electrodes with different graphite weight percentages, 30-70% graphite-polyurethane w w(-1), were morphologically studied by atomic force microscopy (AFM) and voltammetry. AFM images and r.m.s. roughness measurements demonstrated that the polyurethane roughness decreased with increasing the graphite content, composites of 50% and 60% graphite-polyurethane w w(-1) showing the smother electrode surface. The electrochemical characterisation was performed in solutions of K4Fe(CN)(6) by cyclic voltammety and impedance spectroscopy. For compositions of 60% and 70% graphite-polyurethane w w(-1), the cyclic voltammetry results showed the K4Fe(CN)(6) system reversibility. The charge transfer resistance, determined from the EIS spectra, decreased significantly with increasing the graphite/polyurethane ratio, and the capacitance increased for higher graphite percentages. AFM and voltammetric results enable to conclude that 60% graphite-polyurethane w w(-1) was the optimal composition for the preparation of the graphite-polyurethane composite electrodes. (C) 2014 Elsevier B.V. All rights reserved.