Mesoporous Al-MCM-41, Zn- and Fe-Al-MCM-41 molecular sieves with different metal contents were synthesised hydrothermally. The hexagonal structure of synthesised materials was confirmed by low angle XRD. The textural properties were measured by nitrogen adsorption studies. Al-27 MAS NMR was used to study the co-ordination environment of aluminium. Diffuse reflectance spectra (DRS) and electron paramagnetic resonance (EPR) studies also confirm the co-ordination environment of Fe in Fe-Al-MCM-41 framework. The acidity of the catalysts was measured by TPD of NH3 and pyridine adsorbed FT-IR spectroscopy. t-Butylation of phenol with t-butyl acetate (TBA), a 14 new alkylating agent was carried out in vapour phase over the mesoporous materials. For comparison purpose Zn and Fe ion exchanged Al-MCM-41 were also used. The effect of feed molar ratio, phenol space velocity and reaction temperature were studied and the results are discussed. Conditions were optimised to get better phenol conversion and 4-t-butyl phenol (4-TBP) selectivity. (C) 2003 Elsevier B.V. All rights reserved.