The procedure for modification of the step-function method that is used for numerical solution of the linear integral equations, which appear in modelling of the voltammetric experiments, is described. The modification introduces complete numerical integration of all integrals that arise in the integral equation. The methodology is tested on the modelling of the simple diffusion controlled reversible electrode reaction and the reversible EC reaction coupled by partial adsorption of the redox couple. The solutions obtained by the exact and modified step-function methods have been compared and the relative error introduced by modification has been estimated for both electrode reactions. The capabilities of the proposed methodology have been demonstrated by modelling of the complex electrode mechanism, i.e. the catalytic electrode reaction coupled with adsorption of the reactant of the redox couple, which has not been theoretically accessible so far. (C) 2003 Elsevier Science B.V. All rights reserved.