Hydroxybenzophenones are important precursors used in fine chemical and pharmaceutical industries. The esterification reaction of phenol with benzoic acid, followed by the Fries rearrangement towards hydroxybenzophenones in a one-pot liquid phase operation was examined with several catalysts under solvent-free conditions. Cesium substituted dodecatungstophosphoric acid supported on K-10 clay (designated as Cs2.5H0.5PW12O40/K-10) Was found to be the most active and selective catalyst towards 4-hydroxybenzophenone in comparison with others. The order of activity was as follows: 20% w/w Cs2.5H0.5PW12O40/K-10 (most active) similar to (almost equal)UDCaT-5 > 20% w/w Cs2.5H0.5PW12O40/HMS > UDCaT-6(least). The conversion of benzoic acid and selectivity for 4-hydroxybenzophenone at a phenol to benzoic acid mole ratio of 7:1, using 0.05 g/cm(3) Cs2.5H0.5PW12O40/K-10 at 200 degrees C were 70% and 32.5%, respectively. The effects of various reaction parameters on the rate of reaction and selectivity were investigated. (C) 2008 Elsevier B.V. All rights reserved.