Electrochemical polymerization of benzene was carried out in liquid SO2 and in the presence of strong acids such as CF3SO3H, H2SO4, fuming H2SO4 and CH3SO3H. Polyparaphenylene (PPP) films obtained using CF3SO3H exhibited high redox capacity and were characterized by cyclic voltammograms with sharp, well separated redox peaks, while PPP films prepared using other acids showed normal, broad redox peaks. It is shown that the redox capacity of these PPP films depends on the nature of the acid, the temperature, the amount of charge consumed for its preparation and the benzene to acid ratio.