The rate constants and activation energy have been determined for the alkylation of phenol by C-8-C-12 olefins of n- and branched structure in the presence of a catalyst sulphonated copolymers of styrene and divinylbenzene (KU-2kh8). Compared with homogeneous catalysis by p-toluenesulphonic acid, KU-2kh8 slows down the formation of isomeric di- and o-mono-sec-alkylphenols and di-tert-alkylphenols and accelerates the formation of p-mono-alkylphenols, and also the dealkylation of di- and omono-tert-alkylphenols.