Mesoporous AIMCM-41 molecular sieves were synthesized using various aluminium sources, viz., sodium aluminate, aluminium sulphate, aluminium isopropoxide and pseudoboehmite. The influence of different aluminium sources on the framework substitution of aluminium as well as on the catalytic properties of t-butylation of phenol was studied. Among the aluminium sources, the use of sodium aluminate for the AIMCM-41 synthesis showed maximum incorporation of aluminium in the framework. Further, the catalyst also showed good catalytic activity for the chosen reaction. (C) 2000 Elsevier Science B.V. All rights reserved.