One of the key problems in the application of conducting polymer membranes in the analytical ionic potentiometry is a high redox sensitivity of the polymer films, i.e. the open-circuit potential dependence on the solution redox potential. In this work the influence of the solution redox system charge transfer kinetics and its concentration on the observed ionic potentiometric responses of poly(pyrrole) films was investigated. In the theoretical considerations two different processes were distinguished: (a) spontaneous polymer charge/discharge process occurring due to irreversible redox reactions involving the polymer film and (b) fast charge transfer reactions with the redox system in solution. According to the model calculations, in the presence of a strongly irreversible redox couple in solution (e.g. O-2/H2O) alteration of the electrolyte concentration is followed by polymer open-circuit potential changes, i.e. the typical ionic potentiometric calibrations are observed. On the other hand, for a fast redox system in the solution, the polymer open-circuit potential is constant and equal to the equilibrium potential of the redox. couple. In the presence of both redox systems mentioned above, the potentiometric responses are affected by the concentration of redox reactants and a transition from typical ionic to pure redox response is observed. The above theoretical considerations are in good agreement with experimental results obtained for both anion and cation exchanging poly(pyrrole) films (doped with either chloride or hexacyanoferrate anions, respectively): (a) in the presence or absence of dissolved oxygen, (b) in the presence of deliberately added Fe(CN)(6)(3-/4-) or Fe(III)/Fe(II) redox systems.