An improved method of manufacture of a bisphenol comprises heating a monohydric phenol to a first temperature sufficient to melt the monohydric phenol; adding a carbonyl compound to 2.0-3.0 molar equivalents, based on the moles of carbonyl compound, of the monohydric phenol in the presence of catalytic amounts of an organosulfonic acid catalyst and a reaction promoter at a second temperature sufficient to maintain unreacted monohydric phenol in a molten state; increasing the temperature to a third temperature higher than the second temperature, and mixing for a time sufficient to produce the bisphenol in a yield of 80 to 100%, based on the amount of carbonyl compound; wherein mineral acids, Lewis acids, and ion exchange resins are not used. The method is applicable to the manufacture of 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, a useful intermediate for the manufacture of bi-functional poly(phenylene ether)s.