[en] Hydrogenation of C₆₀ at 2 GPa and 723-823 K was performed with thermal decomposition of LiAlH₄ as a hydrogen source. Analysis of hydrogenation products showed that the method can produce not only C₆₀H₃₆, but also hydrofullerides C₆₀H _x with 44 < x < 52. Unlike other hydrogenation methods in which pristine C₆₀ reacts with hydrogen, the high pressure/high temperature conditions result first in C₆₀ 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 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 atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry