The change in the electrical properties were investigated as a function of relative humidity by several techniques (among them the electrochemical impedance) for different ion-conducting polymers, sprayed as films on interdigitated gold electrodes. It was found that the equations valid for electrolytic solutions fit the experimental data. In particular, the Onsager equation, applied to the relevant parameters of the polymeric films, describes the change in the film resistance as a function of relative humidity satisfactorily.