3,4-Dihydropyrimidin-2(1H)-ones derivatives were synthesized in moderate to high yields in one-pot three component reaction from the corresponding aldehydos, ketones or 1,3-dicarbonyl compounds and urea, in the presence of catalytic amount of KAI(SO4)(2)(.)12H(2)O (Alum) supported on silica gel (Alum-SiO2) as a non-toxic, reusable, inexpensive and easily available reagent, under solvent-free conditions at 80 degrees C. Compared to the classical Biginelli reaction, this new method consistently has the advantage of good yields. (c) 2005 Elsevier B.V. All rights reserved.