The use of a solid-phase microextraction (SPME) method with a new design of functionalized stable overoxidized sulfonated polypyrrole (OSPPy) film electrode to extract metal ions (Ni(II) and Cd(II)) without derivatization from water of high saline content is described. Different cation uptake behavior is obtained for OSPPy and overoxidized polypyrrole. The cation uptake and release properties of the OSPPy film electrode were examined under both open circuit and controlled potential conditions for prospective applications in electrochemically controlled solid-phase microextraction (EC-SPME). The cation uptake is enhanced if a positive potential is applied to the electrode. Accumulated cations are released rapidly from the film if the applied potential is switched to a negative value. The cation uptake and release mechanism is affected both by the cation exchange at the negative sulfonate and carboxylate groups on the film and by the altered solution pH occurring at the counter electrode caused by the applied potential. Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) measurements on the two films have confirmed the presence of a sulfur content in the films and shown that covalently bound sulfonate preferentially dopes the polymer even in the presence of a large excess of BF4- anions. Our preliminary fundamental results show that this new polymer offers a wide potential range for electroanalytical exploration from selective electrodes to separation and/or preconcentration sampling devices. (C) 2004 Elsevier B.V. All rights reserved.