The synthesis and properties of the conductive polymer precursor polybenzvalene (I) and its conversion to polyacetylene (II) are presented. I was synthesized by ring-opening metathesis polymn. of benzvalene with non-Lewis acidic tungsten alkylidene catalysts. Treatment of I with solns. of HgCl2, HgBr2, ZnI2, and AgBF4 resulted in a C-C bond rearrangement and produced II. The II films produced with HgCl2 displayed the highest conductivities and the best mech. properties. The II produced was of low crystallinity and upon treatment with iodine exhibited conductivities of 1 S/cm. Oriented II was produced by stretching I and converting it to II. With iodine doping, the oriented II (6-fold stretching) displayed a cond. of 49 S/cm. [on SciFinder(R)]