Abstract: The invention concerns a process for synthesizing 9,9-bis(hydroxyphenyl)fluorene by reacting fluorene with excess phenol using a liquid catalyst prepared by dissolving aluminum trichloride in an anhydrous organic solvent such as toluene evincing the property of an electron donor while hydrochloric-acid gas is being supplied. For the purpose of the synthesis, the fluorenone is dissolved for instance at 60.degree. C. in the liquid phenol and then the liquid catalyst is dripped into the agitated reaction mixture at such a rate that the temperature of the reaction mixture is kept below 60.degree. C. Following catalyst addition and subsequent after-reaction interval of several hours, the raw product is mixed with hot water and the excess phenol is removed by steam distillation. After signle-washing with water, the raw product is dissolved in hot acetone, allowed to crystallize, is filtered out and dried in vacuum. Lastly the raw product is recrystallized from 1,2-dichloroethane to form the pure product.