The aim of this paper is to find a general mathematical expression for amperometric enzyme kinetics problems. The variational iteration method coupled with Pade approximation (VIM-Pade) is used to attain a reliable mathematical expression based on the rational functions. The accuracy of the results is shown in two cases of the electrochemical polymerization on the electrode surfaces. The comparisons indicated that the presented mathematical expression is not only a general model-which could be used in most amperometric enzyme kinetics problems-but also gives more accurate results than the mathematical expressions previously developed for such problems. (C) 2013 Elsevier B.V. All rights reserved.