Esterification kinetics of propanoic acid with ethanol, 1-propanol and butanol over a fibrous polymer-supported sulphonic acid catalyst (Smopex-101) was studied. Experiments were carried out in a batch reactor operating isothermally at three different temperatures: 60, 70 and 75 degrees C (80 degrees C for butanol) and with different initial molar ratios of propanoic acid and alcohol (1:1, 1:2 and 2:1). The fiber catalyst was active and stable in all the experiments. The experimental results were modeled according to a Langmuir-Hinshelwood model and with an advanced adsorption-based model. The activity coefficients were calculated according to the UNIFAC model. The activation energy of esterification of propanoic acid with ethanol was found to be 52.6 kJ/mol, 49.9 kJ/mol with 1-propanol and 47.3 kJ/mol with butanol. The kinetic model, which includes the adsorption of carboxylic acid and water combined with the activities of the species, explained the experimentally recorded concentrations well. (c) 2005 Elsevier B.V. All rights reserved.