Hybrid organic-inorganic MCM-41 silicas functionalized with perfluoroalkylsulfonic acid groups analogous to that of Nation were prepared in a simple single step by a condensation reaction between surface silanol groups of the mesoporous silicas and 1,2,2-trifluoro2-hydroxy-1-trifluoromethyl-ethane sulfonic acid Beta-sultone. The catalysts showed very high activity for the esterification of long-chain fatty acids with ethanol and high-molecular-weight alcohols with essentially complete selectivity at high conversion (> 95%). Acylation of anisole was also possible, with high selectivity for 4-methoxyacetophenone. The catalysts showed more activity conversion than commercial Nafion-silica composite catalysts. (c) 2005 Elsevier Inc. All rights reserved.