Vapour pressures of (butanone + methanol or ethanol) at six temperatures between 278.15 K and 323.15 K were measured by a static method. Excess enthalpies and volumes of mixtures containing methanol were also measured at T = 298.15 K. Reduction of the vapour pressures to obtain activity coefficients and excess molar Gibbs free energies was carried out by Barker’s method. Azeotropic mixtures with a minimum boiling temperature were observed and the azeotropic coordinates were calculated. The experimental results are analyzed in terms of the specific interaction between the hydroxyl hydrogen of the alcohol and the ketoxy group.