The poly(propargyl acetate) (A) having a helical cis–transoid structure was stereospecifically prepared using the Rhcomplexcatalyst, [Rh(norbornadiene)Cl]2, in MeOH or NEt3 solvent at 0 and 40 °C in moderate yield. Electron spin resonance (ESR) analysis of the polymer revealed the formation of the cis (B) and trans (C) radicals which were produced through the thermal rotational scission of the helical