The effect of alkoxy substituents on the physical and electronic properties of a series of poly{1,4-bis[2-(3,4-ethylenedioxy)thienyl]-2,5-dialkoxybenze}s is reported. Monomers containing methoxy, heptoxy, dodecyloxy and hexadecyloxy substituents were obtained from Negishi couplings in yields ranging from 42 to 83%. The methoxy, heptoxy and dodecyloxy monomers electropolymerized efficiently to form electroactive films, with irreversible monomer oxidation peak potentials ranging from +0.46 to +0.51 V versus Ag/Ag+. The hexadecyloxy-substituted derivative exhibited a higher oxidation potential of +0.66 V and a slower rate of film formation owing to solubility of the oligomer. Cyclic voltammetry of the polymer films revealed reversible redox processes with quite low E-1/2,E-p potentials ranging from -0.28 to -0.35 V. Band gaps of 1.75 eV for the methoxy-substituted polymer and 2.0 eV for the longer-chain-substituted polymers were determined from the onset of the pi to pi* transition observed by optoelectrochemical techniques. Oxidative chemical polymerization of the dodecyloxy and hexadecyloxy monomers with ferric chloride, followed by reduction with ammonium hydroxide, produced slightly soluble polymers.