The polymerization was carried out by MoCl5 and WCl6 associated with various organometallic cocatalysts. MoCl5-based catalysts were found to be more effective. Polymerization of monomer containing a spiro structure proceeded rapidly to reach 80% yield within 2 h at 30 degrees C. Polymerization of monomer led to a soluble, purple colored polymer with number average molecular weight ((M) over bar(n)) of 50000. Elemental analysis, H-1-NMR, C-13-NMR, IR, and UV-visible spectra of the resulting polymer indicated that the polymer contains alternating double and single bonds along the polymer backbone and a cyclic recurring unit with a double spiro structure. In addition, the polymer had good oxidative and thermal stability and good solubility in common organic solvents.