Produce new 4,4'-dihydroxyphenyl bicyclohexenes that are useful as a material for liquid crystal polyester, polycarbonate, polyurethane or other synthetic resins or for photoresist used with display elements, semiconductors, etc., by thermally decomposing 4,4,4'4'-tetrahydroxyphenyl bicyclohexanes, preferably in the presence of alkali catalyst.