A composition comprising a) at least one polyheteroaromatic compound or one polyaniline in oxidized, polycationic form, and b) at least one polyanion of a film-forming thermoplastic polymer having sulfonate-alkylated alcohol groups ##STR1## in structural repeating units, wherein the group --(C.sub.n H.sub.2n)-- is linear or branched C.sub.2 -C.sub.12 -alkylene that has from 2 to 5 carbon atoms in the carbon chain and is unsubstituted or substituted by C.sub.1 -C.sub.4 alkoxy. The composition is electrically conductive and can be processed thermoplastically. It can be used in the production of moulded articles or in the form of powders as a filler for plastics.