Five potentiometric pH sensors based on thin polymer films, obtained from electropolymerization of their respective monomers: 1,3-diaminopropane, diethylenetriamine, pyrrole, p-phenylenediamine and aniline, were compared. All these molecules have been chosen since they contain amino groups, which are sensitive to proton concentration changes. The resulting sensors consist in a polymer-coated smooth platinum wire protruded from glass sheath. Their potentiometric responses appeared linear in the range from pH 2 to 11. These electrodes present also a good reversibility and a good stability in time over a period of 1 month. The response mechanisms are also examined. (c) 2005 Elsevier Ltd. All rights reserved.