Mixtures of polyaniline with different polymeric materials were used in order to obtain mechanically stable matrices employed to prepare membranes and coated platinum electrodes. Potentiometric measurements were carried out in aqueous solutions containing either salts or acids of several anions. These measurements indicate that the matrices are more permeable to anions than to cations. The results obtained are dependent upon the radii and charge of the anions investigated. Also, the ionic mobility inside the matrices appears to be higher for protons than for other cations.