In the paper, we have considered possible causes responsible for the fact that CV-curves of electrodes modified by polymer metal complexes with the Schiff bases possess some shoulders or split into two peaks, while the total electrode process has a one-electron character. This study includes a quantitative analysis of voltammetric responses of electrodes, the modifying films of which contain, beside mobile charge carriers (counter-ions), two kinds of immobile ones. Three cases of polymer films are the object of the corresponding description, namely systems combining such charge carriers formed either independently of each other or due to some conversions between them. The obtained results are in a qualitative agreement with those observed in experimental conditions. (C) 2013 Elsevier Ltd. All rights reserved.