Alkylation of phenol with tert-butyl alcohol (TBA) was carried out in batch mode over a zeolite catalyst, synthesized from fly ash by hydrothermal treatment. The effects of various parameters, such as reaction temperature, reactant ratio (molar ratio of phenol to tert-butyl alcohol) and catalyst loading on the rate of reaction of phenol were studied with the synthesized catalyst. The alkylation reaction was found to be surface reaction controlled with negligible mass transfer resistance. An Langmuir-Hinshelwood-Hougen-Watson (L-H-H-W) surface reaction controlled kinetic model was developed and the model parameters were estimated. From the estimated kinetic constant at different temperatures, the activation energy of the phenol alkylation reaction was determined to be 37.3 U/mol. (c) 2005 Elsevier B.V. All rights reserved.