The polymerization of 2-ethynylfuran was carried out by WCl₆ or MoCl₅ associated with cocatalysts such as organotin and oranoaluminum.compounds under various reaction conditions. The effects of monomer to catalyst mole ratio, solvent, cocatalyst, and temperature on the polymerization were studied. The highest yield (43%) and the highest molecular weight (Mn : 12,000) were obtained when the mole ratios of 2-ethynylfuran to WCl₆ as a catalyst and WCl₆ to n-Bu₄Sn as a cocatalyst are 100 and 4, respectively. Ccl₆-based catalysts were more effective than MoCl₅-based catalysts. Poly(2-ethynylfuran) (PEF)s obtained were partially soluble in organic solvents such as chloroform, toluene and 1,2-dichloroethane. The nuclear magnetic resonance, infrared, and ultraviolet-visible spectra indicated that the resulting soluble polymer has a linear conjugated polyene structure containing furyl substituents. Copolymerization of 2-ethynylfuran with 2-ethynylthiophene exhibited lower reactivity of 2-ethynylfuran in comparison with 2-ethynylthiophene.