Soluble polyphenylene (PPH) homopolymers with a controlled polymer chain structure were synthesized for the first time by the complete dehydrogenation of poly(1,3-cyclohexadiene) (PCHD) having a 1,2-addition (1,2-CHD unit) and 1,4-addition (1,4-CHD unit). The reactivity of PCHD for dehydrogenation strongly depends on the polymer chain structure. The rate of dehydrogenation is fast on a long sequence of 1,4-CHD units, while it is considerably impeded by the presence of 1,2-CHD units in the polymer chain. With a reaction temperature higher than 90 degrees C, complete dehydrogenation of PCHD proceeds successfully to yield soluble PPH homopolymers. The polymers obtained are soluble in polar solvents. Therefore, the soluble PPH homopolymers appear to be polar macromolecules, and the conversion of polarity occurs during the dehydrogenation process. UV and fluorescence spectra clearly indicate the nature of a conjugated PPH homopolymer.