Effectivenesses of 2,6-ditertiarybutyl cathecol (Dnx), tri(mono-and-di-nonyl mixture) phosphite (Plg), and their mixtures as antioxidants for CBR are determined. The activatior energies of oxidative degredation for CBR are calculated. An attempt is made to corrolate the results obtained from experimental studies to storage time of CBR under ambient conditions. The relevant experiments are done mainly by differential scanning calorimetry. IR spectroscopy is used for effectiveness studies near room temperatures. Quantitative determinations of antioxidants in CBR samples are carried out by UV spectroscopy. It is found that, as an antioxidant, Dnx is more effective than Plg. When their mixture is used, 60% addition of Plg to Dnx gives almost the same effectiveness. When 45% Plg is added, maximum effectiveness is achieved and Plg is synergist to Dnx. Activation energies calculated are in good agreement with the values given in the literature. To corrolate the retarded oxidation periods obtained from DSC studies to room temperatures, DSC studies at temperatures where relative effectivenesses of different antioxidants to each other do not change by temperature must be carried out.