The polymerization of 1-methoxy-1-ethynylcyclohexane (MEG) was carried out by various transition metal catalysts. The catalysts MoCl5, MoCl4, and WCl6 gave a relatively low yield of polymer (less than or equal to 16%). The catalytic activity of Mo-based chloride catalyst was greater than that of W-based chloride catalyst. However, catalyst tungsten carbene complex (I) gave a larger molar mass and higher yield in the presence of a Lewis acid such as AlCl3 than in the absence of a Lewis acid. The activity of the tungsten carbene complex was obviously affected by Lewis acidity. The catalyst PdCl2 was a very effective catalyst for the present polymerization and gave polymers in a high yield. The structure of the resulting poly (MEC) was identified by various instrumental methods as a conjugated polyene structure having an alpha-methoxycyclohexyl substituent. The poly (MEC)s were mostly light-brown powders and completely soluble in various organic solvents such as tetrahydrofuran (THF), chloroform (CHCl3), ethylacetate, n-butylacetate, dimethylformamide, benzene, xylene, dimethylacetamide, 1,4-dioxane, pyridine, and 1-methyl-2-pyrrolidinone. Thermogravimetric analysis showed that the polymer started to lose mass at 125 degrees C and that maximum decomposition occurred at 418 degrees C. The x-ray diffraction diagram shows that poly (MEG) has an amorphous structure.