Cyclic voltammetry of KI at high concentrations was studied on Pt and polyaniline-modified Pt electrodes in 0.1 M HC1O(4) solution. The oxidation of iodide to iodine proceeded at a polyaniline-filmed Pt electrode with a mechanism similar to that at a bare Pt electrode. New peaks appeared in the cyclic voltammograms on the polyaniline-filmed Pt electrodes, depending on the experimental conditions, due to interactions of iodine species with the polyaniline chains. XPS analysis of polyaniline samples doped with iodine during, or after, the synthesis of polyaniline provided further evidence of the existence of polyaniline-iodine charge transfer complexes.