The surface of indium tin oxide (ITO) and graphite + polymer composite electrodes can be modified by Nafion(R) films containing a little amount of dispersed electroactive substances, such as phthalocyanines. This procedure allows the recovery of electroanalytical information on the electroactive deposited substance. The preparation methods for these types of modified electrodes are discussed from the voltammetric results obtained in this work. The Nafion(R) net acts as a permeable membrane to the hydrogen ions. Furthermore. the presence of methylviologen within the Nafion(R) film makes the electron transport throughout this membrane easy.