The sorption behaviour of a polymer-supported sulphonic acid catalyst, Smopex-101, was studied in different solvent mixtures at 60 and 70 degrees C. The physical characteristics of the catalyst were investigated. Six catalysts with activities, ranging from 2.1 to 3.6 mmol/g, various degrees of cross-linking, 0%, 0.5%, 2% and 4% divinylbenzene as well as dimensions (lengths and diameters) were studied. The analyses of the liquid phase were carried out by using a densitometer. Catalyst swelling was studied with pure solvents as well as in acetic acid-ethyl acetate mixtures. The sorption phenomenon was found to be a complex one depending on the catalyst swelling. (c) 2005 Elsevier B.V. All rights reserved.