Hydrogenation of C 60 at 2GPa and 723–823K was performed with thermal decomposition of LiAlH 4 as a hydrogen source. Analysis of hydrogenation products showed that the method can produce not only C 60 H 36 , but also hydrofullerides C 60 H x with 44<x<52. Unlike other hydrogenation methods in which pristine C 60 reacts with hydrogen, the high pressure/high temperature conditions result first in C 60 polymerization into a tetragonal phase which later reacts with hydrogen. It is suggested that hydrogen first attacks intermolecular carbon–carbon bonds, resulting in complete depolymerization of C 60 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 C 60 . Hydrogenated polymeric C 60 was identified as an intermediate reaction product. Characterization of highly reduced material was performed by Raman and IR spectroscopy, X-ray diffraction, and atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry.