Numerical simulations of cyclic voltammograms corresponding to a catalytic EC' reaction taking place at a thin film modified electrode are performed by way of finite difference method. Besides considering the chemical kinetic occurring inside the thin film, the model takes into account the different diffusion coefficients for each species at each of the involved phases, i.e. the thin film layer and bulk solution. The theoretical formulation is given in terms of dimensionless model parameters but a brief discussion of each of these parameters and their relationship to experimental variables is presented. Special emphasis is given to the use of working curve characteristics to quantify diffusion coefficient, homogeneous kinetic constant and thickness of the thin layer in a real system. Validation of the model is made by comparison of experimental results corresponding to the electron charge transfer of Ru(NH3)(6)(3+)/Ru(NH3)(6)(2+) hemi-couple at a thin film of a cross-linked chitosan film containing an immobilized redox dye. (C) 2012 Elsevier Ltd. All rights reserved.