The catalytic properties of zeolite beta in the tert-butylation of phenol are reported. The influence of various reaction parameters such as temperature, space velocity, molar ratio of the reactants are discussed. Medium acid sites on zeolite H beta are advantageous in producing p-TBP, and that of strong acid sites are helpful for the formation of 2,4-DTBP, while weak acid sites are effective in producing o-TBP. In order to enhance the selectivity of p-TBF, a proper reaction temperature (418 K), lower reactant ratio (molar ratio) and moderate acidities on zeolite H beta are recommended. On the basis of the behaviour obtained in the cases mentioned, information about the reaction path models is provided.