The oxidation of C-60 and C-70 fullerites and C-60/C-70 mixture is accompanied by the decomposition of the carbon frameworks of the molecules at annealing temperatures of 250 and 445 degrees C. Fourier-IR and HPLC studies show that the oxidation/decomposition of C-70 molecules is more active than that of C-60. The stages of fullerite interaction with oxygen while heating in air were determined.