Method for preparing 5,5'-diamino-2,2'-bisthiophene or -bisthiazole derivatives (X), or their salt-like oxidation products. Method for preparing 5,5'-diamino-2,2'-bisthiophene or -bisthiazole derivatives (X), of formulae (1) or (2), or their salt-like oxidation products comprises conventional preparation of the corresponding 2-unsubstituted heterocycle then reacting this with an oxidizing agent free of heavy metals, in a solvent at 0-100[deg]C, preferably room temperature. [Image] R1> and R2>alkyl (e.g. Me, Et or substituted propyl), aryl (e.g. phenyl, naphthyl, anthryl, phenanthryl or pyrenyl), or, optionally substituted once, a heteroaromatic group (e.g. (benzo)thienyl, (benzo)thiazolyl, pyridyl, quinolyl or quinazolinyl), or together with the N atom form a heterocyclic fragment, e.g. phenothiazinyl, phenoxazinyl or phenodiazinyl; and R3> and R4>hydrogen, alkyl or aryl (e.g. as above) or a heteroaromatic group (e.g. as above), all optionally substituted once.