The electrochemical and microstructural properties of carbon film electrodes made from carbon film electrical resistors of 1.5, 15, 140 Omega and 2.0 k Omega nominal resistance have been investigated before and after electrochemical pre- treatment at +0.9 V vs SCE, in order to assess the potential use of these carbon film electrodes as electrochemical sensors and as substrates for sensors and biosensors. The results obtained are compared with those at electrodes made from previously investigated 2 Omega carbon film resistors. Cyclic voltammetry was performed in acetate buffer and phosphate buffer saline electrolytes and the kinetic parameters of the model redox system Fe(CN)(6) (3) (/4) obtained. The 1.5 Omega resistor electrodes show the best properties for sensor development with wide potential windows, similar electrochemical behaviour to those of 2 Omega and close-to-reversible kinetic parameters after electrochemical pre-treatment. The 15 and 140 Omega resistor electrodes show wide potential windows although with slower kinetics, whereas the 2.0 k Omega resistor electrodes show poor cyclic voltammetric profiles even after pre-treatment. Electrochemical impedance spectroscopy related these findings to the interfacial properties of the electrodes. Microstructural and morphological studies were carried out using contact mode Atomic Force Microscopy (AFM), Confocal Raman spectroscopy and X-ray diffraction. AFM showed more homogeneity of the films with lower nominal resistances, related to better electrochemical characteristics. X-ray diffraction and Confocal Raman spectroscopy indicate the existence of a graphitic structure in the carbon films. (c) 2008 Elsevier B.V. All rights reserved.