Hydrogenation of C-60 by the cathodic electrolytic reduction of C-60 coated on a graphite cathode was carried out using 30 weight percent KOH-H2O solution as electrolyte. By cyclic voltammetry, the cathodic potential in the electrolytic reduction was estimated to be -1.4 V vs. Ag/AgCl. After the reduction of C-60, the formation of C60H2 was identified by negative-ion fast atom bombardment mass spectroscopy and electronic spectroscopy as well as high performance liquid chromatography. By anodic oxidation of the formed C60H2, C-60 was identified by several characterization methods. The hydrogenation of C-60 and dehydrogenation of C60H2 by electrolysis is reversible.