AbstractAlkylation of phenol with isobutene catalysed by Amberlyst 15 (cation exchange resin) was carried out in a batch reactor in the liquid phase. The reaction rate increased with increase in catalyst concentration and reaction temperature. Resin particle size and stirrer speed had virtually no effect on the rate under the experimental conditions. The rate data were correlated with a kinetic model based on homogeneous reaction. The apparent activation energies were found to be 57.7, 51.5 and 46.4 kJ mol‐1for the formations ofo‐alkylate,p‐alkylate and dialkylate respectively. The resin was found to have higher selectivity than the sulphuric acid cat