The UNIQUAC associated-solution model has been applied to reproduce vapour-liquid equilibria and excess molar enthalpies for binary mixtures containing one alkanoic acid and one alkanol and then to predict ternary excess molar enthalpies for acetic acid + methanol + tetrachloromethane. Furthermore, the model has been modified to include additional parameters in order to obtain a better correlation of vapour-liquid equilibria of strongly non-ideal mixtures involving at least one alkanol. The calculated results agree well with the experimental values for many systems studied.