The influence of the electrochemical pretreatment (potentiodynamic cycling) and previous conditioning of thick cation sensitive PPB films (30 mu m) doped with sulphate, naphthalene-2-sulfonate (N-2-S) and naphthalene-1,5-disulfonate (N-1,5-DS) on the electrochemical properties were studied. The changes in the chemical composition of the PPy films were determined by electron probe microanalysis (EPMA). The poor mobility of dopant anions in the film and participation of cations in the PPy film redox process is the basis of their cation sensitivity. The influence of potentiodynamic cycling on the properties of these PPy films is correlated with the change of several factors, such as the redox activity in the potential interval of the potentiometric measurements, the redox capacity, the ionic content and the quality of contact with the substrate. The long-term conditioning of the PPy electrode in a certain solution is necessary for the achievement, maintenance or re-establishment of the stable quasi-equilibrium state of PPy film characterized by a quasi-equilibrium potential E-r. The conditioning process of the untreated PPy\N-2-S and PPy\N-1,5-DS electrodes proceeds very slowly. It accelerates after potentiodynamic cycling, enabling the use of the electrodes for potentiometric measurements after only 2 days of conditioning. The potentiodynamic cycling of the PPy electrodes doped with big organic anions improves also their potentiometric response, extending considerably the linear parts of E-log a plots towards low concentrations. The nature of this effect consists in the change of a thick PPy film to become redox active in the potential region of the potentiometric measurements.