A star-shaped poly(1,3-cyclohexadiene) (PCHD) with a fullerene-C-60 (C-60) core (C-60-PCHD) was prepared to examine the thermal stability of the covalent bond between the C-60 and PCHD arm in the C-60-PCHD. The covalent bond between the C-60 and PCHD arm formed by a 1,2-cyclohexadiene (CHD) unit on the C-60 was stronger than that formed by a 1,4-CHD unit. The double bond in the CHD unit adjoining the C-60 core was a key structure for the stability of that covalent bond. The hydrogenated C-60-PCHD, which did not contain a double bond, possessed significantly higher thermal stability compared to C-60-PCHD. The mechanism of elimination of PCHD arm molecules from the C-60 core was thought to proceed via a 1,5-sigmatropic H-shift. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2132-2142, 2009