AbstractPolyacetylene was doped from solution with dihydrogen hexachloroiridate (H2IrCl6·6H2O), and also doped electrochemically with tetra‐n‐butylammonium hexachloroiridate(IV) (NBu4)2IrCl6·6H2O to form electrically conductive complexes. The doped polymer was characterized by ultraviolet, visible, and infrared spectroscopy, X‐ray diffraction, EPR spectroscopy, transmission electron microscopy, and electrical transport measurements. A hydrolyzed hexachloroiridate species was incorporated in the polymer during spontaneous doping with H2IrCl6·6H2O, whereas electrochemical doping with (NBu4)2IrCl6·6H2O resulted in the introduction of the expected hexachloroiridate species. Evidence suggests that, in the case of H2IrCl6·6H2O, doping occurs by a proton acid mechanism. TEM studies indicate that the hexachloroiridate dopant is not distributed homogeneously in the polymer. The stability of hexachloroiridate‐doped polyacetylene was examined in air, in an inert atmosphere, and at high temperatures. In air, the rate of decrease of the conductivity was about one order of magnitude per 28 days, whereas in an inert atmosphere, the conductivity dropped about one order of magnitude