Catalyst for reducing formation of chlorinated dioxins in manufacture of chlorinated phenols

A catalyst used in a process of producing polychlorinated phenols having reduced amounts of chlorinated dioxin formed during the reaction of phenol or lower chlorinated phenols, or mixtures thereof, with chlorine, said catalyst selected from a group consisting of zirconium tetrachloride or hafnium tetrachloride or mixtures thereof, by reacting at a temperature of from 10.degree. C. to 190.degree. C. a phenol selected from the group consisting of phenols and lower chlorophenols and mixtures thereof, and chlorine to form a reaction mixture in the presence of from about 0.005 to about 0.016 moles per mole of said catalyst.