A process for producing a 3,3,5-trimethylcyclohexylidenebisphenol of formula (11):
wherein R 1 and R 2 can be the same or different and represent hydrogen or C 1 -C 4 alkyl, each R 1 substituent being the same or different and each R 2 substituent being the same or different, provided that the R 1 and R 2 substituents on a given phenyl moiety are not simultaneously C 4 alkyl,
which process comprises:

(a) reacting a phenol (A) of formula (I)
wherein R 1 and R 2 are as defined above, with 3,3,5-trimethylcyclohexanone (B) at a molar ratio ((A)/(B)) of from 3 to 7 in the presence of an acid catalyst until the 3,3,5-trimethylcyclohexanone (B) exhibits at least 90 mol% conversion; and
(b) adding a phenol (A) of formula (I) wherein R 1 and R 2 are as defined above and/or an aromatic hydrocarbon (C) to the thus obtained reaction mixture.