Copolymers of 3,4-ethylenedioxythiophene and 3-methylthiophene have been prepared by recurrent potential pulses using monomer mixtures with various concentration ratios, their properties being compared with those of the corresponding homopolymers. In addition, different technological applications have been tested for the generated copolymers. Results indicate that the properties of the copolymers are closer to those of poly(3,4- ethylenedioxythiophene) than to those poly(3-methylthiophene). Furthermore, the ability of the copolymers to store charge and to interact with plasmid DNA suggest that they are very promising materials. © 2007 WILEY-VCH Verlag GmbH & Co. KCaA.