Theory of the charging and discharging process in electron-conducting polymer films at an electrode surface has been presented. It is based on the concept of two coexisting subsystems at the polymer matrix, 'usual' sites P which can exchange with the electrode by the electronic charge in a quasi-reversible manner, and sites D where intermolecular bonds between neighboring polymer molecules can be formed. The charging and discharging of the latter subsystem may be realized along different reaction pathways, e.g. via the bond formation after the generation of two cation radicals within such site D in the course of the anodic scan while the bond dissociation may take place via a partially discharged state of the intermolecular bond. This difference leads to a hysteresis in cyclic voltammograms, first of all to a significant mutual shift of the anodic and cathodic peaks of the current originated from the redox transformations of D sites. An important feature of the P sites extracted from experimental CV data is their broad energetic inhomogeneity (dispersion of their redox potentials) responsible for plateaus of the current observed at high charging levels in both directions of the potential scan. Several approaches to the numerical integration of the kinetic equations for the sites' states have been analyzed, and qualitative predictions of the theoretical model have been illustrated.