The reaction of tert‐butyl hydroperoxide with 2,2′‐methylenebis(4‐methyl‐6‐tert‐butylphenol) in a benzene solution was studied within the temperature range 132 to 170°C. The change in the concentration of both components and the formation of the products were investigated depending on time. The products thus formed were isobutylene, tert‐butyl alcohol, acetone, and the oxidation products of methylenebisphenol. Individual amounts produced depended on the reaction temperature and the initial concentration of the starting compounds. GPC was used for the following transformations of methyl‐enebisphenol. The decomposition of tert‐butyl hydroperoxide was found to be accelerated by the presence of methylenebisphenol, which, however, affects but little the splitting of the tert‐butoxyl radicals yielding acetone.