Method for producing bisphenols

A method for producing a bisphenol is disclosed. The method entails reacting in at least one first reactant selected from a first group consisting of phenol and substituted phenols with at least one second reactant selected from a second group consisting of ketones and diols, in the presence of hydrogen chloride catalyst and volatile sulphur compound having an SH bond as co-catalyst. The reaction product is a mixture that contains bisphenol, first reactant and second reactant. The catalyst and co-catalyst and water of reaction are separated by distillation. The method is characterized by the high reaction rates and selectivities.