Vapour pressures of (butanenitrile + ethanol or butan-1-ol) between the temperatures T = 278.15 K and 323.15 K were measured by a static method. Excess enthalpies and volumes 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 over the whole temperature range. The experimental results are interpreted in terms of the specific interaction between the hydroxyl hydrogen of the alcohol molecule and the lone electron pair on the nitrogen atom.