In a previous work [G. Fetter, G. Heredia, A.M. Maubert, P. Bosch, J. Mater. Chem. 6(11) (1996) 1857-1858.] we reported on the use of microwave irradiation for the synthesis of pillared clays. In this paper we discuss the application of this method to prepare high surface area aluminum-pillared clays from clay suspensions as highly concentrated as 50 wt%. The aluminum pillaring solution was 2.5 M.