Hydrogenation of C60 at 2 GPa and 723-823 K was performed with thermal decompn. of LiAlH4 as a hydrogen source. Anal. of hydrogenation products showed that the method can produce not only C60H36, but also hydrofullerides C60Hx with 44 < x < 52. Unlike other hydrogenation methods in which pristine C60 reacts with hydrogen, the high pressure/high temp. conditions result first in C60 polymn. into a tetragonal phase which later reacts with hydrogen. Probably hydrogen first attacks intermol. carbon-carbon bonds, resulting in complete depolymn. of C60 at a later stage of the hydrogenation process. This model suggests the possibility to select starting points for hydrogenation by choosing specific polymeric structures of C60. Hydrogenated polymeric C60 was identified as an intermediate reaction product. Characterization of highly reduced material was performed by Raman and IR spectroscopy, x-ray diffraction, and atm. pressure photoionization Fourier transform ICR mass spectrometry. [on SciFinder (R)]