The electropolymerization of four tetrathienyl compounds of the carbon group elements (T(4)M, where M = Si, Ge, Sn or Pb) was studied on indium tin oxide electrodes in three organic solvents with low water content (acetonitrile, propylene carbonate and nitrobenzene). Only poorly conducting deposits were obtained in acetonitrile, but polymerization in propylene carbonate yielded partially electroactive films. The best polymers were formed in nitrobenzene, but none of the tetrathienyls tested produced polythiophene films superior to those prepared using thiophene as the monomer with the same experimental conditions. The polymerization mechanism of the thienylmetals is different from that of purely organic thiophene derivatives, as the oxidation produces neutral thiophene radicals in the former case, instead of radical cations. The results suggest that the reactive neutral thiophene radical can abstract a hydrogen atom from solvents such as acetonitrile, explaining the apparent contradiction in the polymerization efficiency of tetrathienyls and thiophene in this solvent.