Abstract: Disclosed is a method of treating hydroperoxide mixtures, which comprises bringing an oily hydroperoxide mixture containing (A) an aromatic hydroperoxide having a hydroperoxymethyl group directly bonded to the aromatic nucleus and (B) an aromatic hydroperoxide having a 2-hydroperoxy-2-propyl group bonded directly to the aromatic nucleus into contact with an aqueous alkali solution, separating the aqueous phase from the oil phase and decomposing at least a part of the component (A) extracted in the aqueous phase.According to this method, the starting oily hydroperoxide mixture can be converted to a mixture in which the primary hydroperoxide content is reduced without substantial loss of the tertiary hydroperoxide. Therefore, aromatic hydroperoxide mixtures suitable for production of phenols can advantageously be proceeded.