The new type of polystyrene with pendent perfluoroalkylsulfonylimide groups polymer (PPFSI or P-SO2NHSO2Rf, where P is the polymer chain, R=-CF3, -CF2CF2CF2CF3) was prepared by chemical modification of chlorosulfanated poly(styrene-co-divinybenzene) resins with perfluoroalkylsulfonylamides RfSO2NH2. Acid strength of the PPFSI was tested by the Hammett indicator method, acid contents of the PPFSI were determined by acid-base titration and the nature of chemical modification for the PPFSI was evaluated by IR, TGA and SEM. The results indicated that the PPFSI was a strongly acidic polymer, which could be tolerant of high temperature, and an effective catalyst for direct condensation of carboxylic acids and alcohols. (c) 2005 Elsevier B.V. All rights reserved.