A (O2) x C60 sample with a high content of oxygen (x ≥ 0.4) and free of technological solvent impurities was obtained by precipitation from solution. For the first time, the results of the determination of the x coefficients using 13C NMR and elemental analysis were compared. It was shown by Raman spectroscopy, mass spectrometry, and NMR that the inclusion of oxygen into fullerite was accompanied by a decrease in the frequency of O=O stretching vibrations by no less than 12 cm−1 compared with gaseous O2. Nevertheless, oxygen exists in the molecular form in (O2)0.4C60 and is released in the form of O2 as the sample is heated to 373 K. The number of oxygen molecules occupying octahedral pores closets to the fullerene molecule takes on all the possible values, from 0 to 6. At room temperature, the (O2) x C60 sample lost oxygen much more slowly than similar products prepared by diffusion saturation of pure fullerite with oxygen.