Four linear dimers of 4-(hexyloxy)phenylacetylene I have been synthesized and thermally polymerized under the same conditions which were used for I. The polymerization of monomer and linear dimer mixtures was also studied. The reaction products were analysed by chromatography, spectroscopy and spectrometry techniques. The experimental results led us to conclude that the linear dimers are not reaction intermediates of the thermal polymerization of I.