Vapour pressures of butanenitrile + 2-methyl-1-propanol or + 2-methyl-2-propanol at several temperatures between 278.15 and 323.15 K were measured by a static method. Excess molar 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 fitting the vapour pressure data to the Redlich-Kister correlation according to Barker’s method. Azeotropic mixtures with a minimum boiling temperature were observed over the whole temperature range, except for 2-methyl-2-propanol at T = 323.15 K.