Alkylation of phenol was carried out with tert-butyl alcohol (TBA) over a variety of non-conventional catalysts, namely fly ash, zeolite prepared from fly ash, and commercial 13X zeolite. Zeolite prepared from fly ash by hydrothermal treatment showed the highest activity for the reaction under otherwise identical conditions. 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 catalyst prepared from fly ash. The alkylation reaction was found to be surface reaction controlled with negligible inter-particle mass transfer resistance.