A novel and simple one-step method for the aluminum catalyzed self-aldol reaction of valeraldehyde is presented. This mechanochemical method utilizes high-energy ball milling to produce fresh aluminum surface in the presence of valeraldehyde as a liquid milling solution. The fresh surface created through the mechanical attrition of aluminum particles during milling is highly reactive, and serves to catalyze the self-aldol reaction of valeraldehyde to form 2-propyl-3-hydroxyl-heptanal. (C) 2009 Elsevier B.V. All rights reserved.