New thiophene derivatives substituted by electrochemically cleavable sulfonamide groups have been synthesised and their electrochemical behaviour has been investigated in acetonitrile. The anodic oxidation of phenyl (I)- and naphthyl (II)sulfonamide-substituted thiophenes yielded corresponding polymer films exhibiting p- and n-doping processes. The cathodic cleavage of the S-N bond grafted to the polymer backbone was performed by applying a potential lower than - 2.5 V (versus Ag \ 10(-1) M Ag+) to the polymer. The efficiency of this solid-state electrochemical reaction was found to be strongly lowered when the him thickness was increased. It was demonstrated that the decrease of this parameter was less important when a copolymer electroformed from II or a phenylsulfonamide-substituted terthiophene (III) was involved. The recycling properties of this type of material were illustrated by the grafting of an aminoferrocene moiety after the cathodic cleavage step to poly(II-co-3-methylthiophene).