The photophysical properties of a novel 1,2,3,4,5,6-hexasubstituted fullerene derivative (1) are examined in this study. In addition to the ground state absorption spectrum of 1, we report its triplet-triplet absorption spectrum and molar extinction coefficient (AεT-T), as well as the triplet quantum yield (φT), lifetime (τT), and energy (ET)- The saturation of a single six-member ring on the fullerene cage results in significant changes in the triplet state properties as compared to that of pristine C66. The triplet-triplet absorption spectrum shows a hypsochromic shift in long wavelength absorption, and both the triplet state lifetime and the triplet quantum yield are decreased. The triplet energy was found to be similar to that of C60. In addition, the quantum yield (ΦΔ) of singlet oxygen generated by 1 was calculated and is found to be significantly less than in the case of C60..