The reaction kinetics of the esterification of acetic acid with ethanol, catalyzed both homogeneously by the acetic acid, and heterogeneously by Amberlyst 15, have been investigated. The reactions were carried out at several temperatures between 303.15 and 353.15 K and at various starting reactant compositions. Homogeneous and heterogeneous reactions have been described using the models proposed by Popken et al. [T. Popken, L. Gotze, J. Gmehling, Reaction kinetics and chemical equilibrium of homogenously and heterogeneously catalyzed acetic acid esterification with methanol and methyl acetate hydrolysis, Ind. Eng. Chem. Res. 39 (2000) 2601-2611]. These models use activities instead of mole fractions. Activity coefficients have been calculated using ASOG [K. Kojima, K. Tochigi, Prediction of Vapor-liquid Equilibria by the ASOG Method, Elsevier, Tokyo, 1979] and UNIFAC (Aa. Fredenslund, J. Gmehling, P. Rasmussen, Vapor-liquid Equilibria Using UNIFAC. A Group Contribution Method, Elsevier, Amsterdam, 1977] methods. A packed bed reactive distillation column filled with Amberlyst 15 has been employed to obtain ethyl acetate. The influence of feed composition and reflux ratio have been analyzed. (c) 2006 Elsevier B.V. All rights reserved.