The degradation of fullerene-C-60 (C-60) end-capped poly(1,3-cyclohexadiene) (C-60-PCHD) with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) was examined to reveal the nature of the covalent carbon carbon bond between C-60 and PCHD (C-60-PCHD bond). The number average molecular weight (M-n) of C-60-PCHD decreased with an increase in the degree of dehydrogenation, and the elimination of a PCHD arm from a C-60 occurred. The degradation of the C-60-PCHD bond via a 1,4-CHD unit was faster than that via a 1,2-CHD unit, whereas the C-60-poly(cyclohexane) bond was stable. The degradation of the C-60-PCHD bond with DDQ was caused by the dehydrogenation of a CHD unit adjoining a C-60 core. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 2923-2931, 2010