A comparative study on tert-butylation of cresols such as o-cresol, m-cresol and p-cresol with tert-butyl alcohol was carried out over 30% 12-tungstophosphoricacid and 12-tungstosilicicacid supported onto neutral alumina in liquid phase under mild conditions. The catalysts show high activity in terms of % conversion and % selectivity for the products, p-tert butyl o-cresol, o-tert butyl m-cresol, o-tert butyl p-cresol, under mild conditions.