Photophysical measurements have been made on 1,2-C70H2, the most stable isomer of the simplest C-70 derivative. This dihydride＇s electronic absorption spectrum is more diffuse than that of C-70 Red shifts in the fluorescence and phosphorescence emission spectra show that excitations to the lowest singlet and triplet electronic states require approximately 8% less energy in 1,2-C70H2 than in C-70 and that the S-1-T-1 gap of 1,2-C70H2 is ca. 310 cm(-1) smaller than that of the parent fullerene. The dominant peak in the dihydride＇s T-n <-- T-1 near-infrared absorption spectrum falls at 1050 nm. Compared to the corresponding transition of C-70, this absorption feature is broadened, red-shifted by 75 nm, and reduced in peak molar absorptivity by a factor of 2. Derivatization of C-70 to form 1,2-C70H2 accelerates T-1 decay by more than an order of magnitude, giving an intrinsic triplet Lifetime of 2.0 ms at room temperature. The rate constant for triplet deactivation through ground stale self-quenching is near 7.6 x 10(7) M-1 s(-1), or approximately twice that of C-70.