The poly(propargyl acetate) (A) having a helical cis-transoid structure was stereospecifically prepared using the Rh complex catalyst, [Rh(norbornadiene)Cl](2), in MeOH or NEt3 solvent at 0 and 40 degrees 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 as C=C bonds in the main-chain during the polymerization. The spatial and geometrical structure was successfully deduced using the two analogues' polymers in which either methyl or methylene group is deuterated, by the aide of computer simulation of the observed ESR spectra together with the calculation of spin density of the two radicals. (C) 2011 Elsevier Ltd. All rights reserved.