TiO2-SO42- has been prepared by the sol-gel method using H2SO4 and used for the synthesis of chalcones under microwave irradiation. Sulfate loading by H2SO4 increases the Lewis acidity of TiO2. This catalyst gives an excellent yield with less reaction time and is an inexpensive, easily recyclable catalyst for this reaction. (c) 2010 Elsevier B.V. All rights reserved.