SBA-15 was synthesized using non-ionic surfactant as the structure directing agent at 40 degrees C. It was then impregnated with different loadings (10, 30, 50 and 70%) of phosphotungstic acid. They were characterized by XRD, N-2 adsorption, FT-IR and DRIFT techniques. The physicochemical characterization revealed that SBA-15 could accommodate discrete phosphotungstic acid due to its large pore volume and high surface area. The catalytic activity of these materials was examined in the vapour phase tert-butylation of phenol using tert-butyl alcohol as the alkylating agent. The influence of reaction parameters such as reaction temperature, reactant feed ratio, WHSV and time on stream was studied, and the results were correlated with physicochemical characteristics of the catalysts. 4-tert-Butyl phenol was observed as the major product with high selectivity. Among the catalysts, 30% phosphotungstic acid supported SBA-15 showed high phenol conversion under optimum conditions, which is significantly higher than either phosphotungstic acid loaded mesoporous AlPO or AlMCM-41. (c) 2006 Elsevier B.V. All rights reserved.