1-Chlorc-2-thienylacetylene was prepared by the reaction of n-butyllithium with 2-(2,2-dichloro-1-fluorovinyl) thiophene which is the product of the reaction between lithiothiophene and 1,1-dichloro-2,2-difluoroethylene(CF₂=CCl₂). The Polymerization of 1-chloro-2-thienylace tylene was carried out by WCl₆ or MoCl₅ with cocatalysts such as organotinor organoaluminium conlpounds under various reaction conditions. An interesting result observed in this investigation is that WCl₆-organoaluminium and MoCl₅-organotin compounds are highly effective catalyst systems. The proton magnetic resonance, infrared, ultraviolet-visible, fluorescence spectra and elemental analysis indicated that the resulting polymer had a linear conjugated polyene structure containing thienyl and chloro substituents. This polymer was found to be stable up to 310℃ by TGA and DSC analyses.