A variety of aromatic gem-dihalides were synthesized for the first time from the reaction of their corresponding aldehydes with acid halides in the presence of acid catalysts. Both homogeneous and heterogeneous Lewis and Bronsted acids were successfully employed. AlCl3 and sulfated zirconia were the most active homogeneous and heterogeneous catalysts respectively. Benzoyl chloride was more reactive than acetyl and propionyl chloride. Replacing the chloride with bromide also resulted in increased activity. Performing the reaction in a polar solvent and in benzaldehyde as a self solvent resulted in a higher product yield. Sulfated zirconia was regenerated and successfully re-used by calcination in static air at 550degreesC for 0.5 h. (C) 2004 Elsevier B.V. All rights reserved.