In this study P2O5/Al2O3 is found to catalyze the preparation of Schiff bases from the reaction of carbonyl compounds with primary amines efficiently under solvent-free conditions. The advantages of this friendly, environmentally and mild method are such as simplicity of the reaction procedure, the elimination of solvents, simple work-up, high product yields and short reaction times. (c) 2006 Elsevier B.V. All rights reserved.