PURPOSE: To obtain a high-MW polymer applicable to a semiconductor, gas adsorbent or polarizing material, by polymerizing a monosubstituted acetylene by use of a catalyst prepared by irradiating a transition metal carbonyl/organic halide mixture with light.

CONSTITUTION: A mixture of a transition metal carbonyl, e.g., tungsten hexacarbonyl, and an organic halide, e.g., CCl4, is irradiated with light. The irradiation is preferably such that the dosage corresponds to that obtained from a 100WW1kW light source placed about 30cm distant for at least 10min, pref., 30minW1hr. A monosubstituted acetylene of the formula, wherein R is a (substituted) alkyl or a (substituted) arly, e.g., phenylacetylene, is polymerized by use of the above-produced catalyst. The amount of the transition metal carbonyl used is suitably 0.1W 10mol%, based on the monomer of the formula. It is possible to obtain a high-MW polymer in high yields.