The cyclic voltammetric response of planar electrodes modified with cylindrical blocks is modeled using finite difference simulations. The validity of the simulation approach employed is verified using experimental data obtained from partially blocked gold electrodes. Comparison of theory with experiment shows that they are in very good agreement. Finally, experimental results combined with simulations are used to analyse the electrochemical behaviour of these modified electrodes and in particular the deviation of the voltammetric response from planar behaviour. It is shown that electrodes, which are significantly blocked and non-flat can show peak currents, which vary with scan rate much as expected for one-dimensional diffusion, testifying to the need for surface analysis/imaging in conjunction with rigorous electrochemical measurements. (c) 2006 Elsevier B.V. All rights reserved.