The synthesis and properties of the polybenzvalene and its conversion to polyacetylene are presented. This conversion is performed by treating polybenzvalene with Lewis acid catalysts. The highest quality material was obtained from the isomerization with HgCl2. The polyacetylene produced by this precursor route has a morphol. that is considerably more amorphous than other forms of polyacetylene that have been previously reported. Orientation of the precursor polymer by stretching induced crystallinity and chain alignment as detd. by x-ray diffraction. The unoriented polyacetylenes exhibited a cond. of 1 $Ømega$-1 cm-1 with I doping. Materials stretched to elongations of l/l0 = 2.3 and l/l0 = 6 displayed conductivities of 13 $Ømega$-1 cm-1 and 49 $Ømega$-1 cm-1, resp. Block copolymers of polynorbornene and polybenzvalene were produced. [on SciFinder(R)]