Poly(3-octylthiophene) (PT8), poly(3-tetradecylthiophene) (PT14) and poly[(3-octyloxy)-4-methylthiophenel (POMT) have been analyzed by cyclic voltammetry in solution and as precast films. All polymers show in both conditions at least two distinct oxidation processes separated by ca. 200 mV. Moreover, although these polymers have a non-planar conformation when in solution and a coplanar structure when in the solid state, these conformational differences are not detected in their respective cyclic voltammograms. It is then assumed that the dissolved polymers may adopt a coplanar conformation in the vicinity of the electrode.