[o‐(Trimethylgermyl)phenyl]acetylene was polymerized in the presence of WCl6, W(CO)6‐hv, etc., to give polymers whose weight‐average molecular weights reached ca. 7.0 X 105 at the highest. When the MoOCl4‐n‐Bu4Sn‐EtOH (1 : 1 : 1) catalyst was used, the polydispersity ratio of the polymer obtained was 1.08, and the number‐average molecular weight increased in direct proportion to monomer conversion; these indicate that this polymerization is a living polymerization. The polymer had the structure [CHC(C6H4‐o‐GeMe3)]n and was a dark purple solid (λmax = 551 nm, εmax = 6100 M‐1 cm‐1 in THF) soluble in organic solvents such as toluene and chloroform. The onset temperature of weight loss of the polymer in TGA in air was ca. 230°C, and the glass transition temperature was above 180°C. The Po2 of the present polymer is 105 barrers—larger than the value of natural rubber and fairly close to that of poly(dimethylsiloxane). © 1993 John Wiley & Sons, Inc.