Kinetic data on the esterification of acetic acid with isobutanol have been obtained from both the uncatalyzed and heterogeneously catalyzed reactions using a stirred batch reactor in dioxane. The equilibrium constant, which is independent of temperature ranging from 318 to 368 K, was found to be 4. The uncatalyzed reaction was proved to be second-order reversible. In the presence of the catalyst, on the other hand, the reaction has been found to occur between an adsorbed alcohol molecule and a molecule of acid in the bulk fluid (Eley-Rideal model). It has also been observed that the initial reaction rate decreases with alcohol and water concentrations and it linearly increases with that of acid. The temperature dependency of the constants appearing in the rate expression were also determined. (C) 2002 Elsevier Science B.V. All rights reserved.