PURPOSE: To obtain the titled compound having a large crystal form in reacting diisopropylbenzene dihydroperoxide, etc. with a sulfite in the presence of an alkali efficiently, by carrying out the reaction in the presence of an organic solvent while removing the organic solvent to the outside of the system.

CONSTITUTION: Diisopropylbenzene dihydroperoxide or (2-hydroxy-2-propyl) cumene hydroperoxide or both are reacted with a sulfite in the presence of an alkali and an organic solvent while removing the organic solvent to the outside of the system by the azeotropic mixture thereof with water in the reaction, preferably the azeotropic mixture with water under reduced pressure, to give the aimed compound useful as a raw material for peroxides, e.g. a radical polymerization initiator, industrially and advatageously. An organic solvent, substantially insoluble in water, and capable of dissolving the aimed compound, particularly hexane, heptane, toluene, benzene and/or methyl isobutyl ketone, may be used as the organic solvent.