The data on molar excess enthalpies, H_m^E, for the binary mixtures acetic acid + n-butanol, acetic acid + n-butyl acetate and n-butanol + n-butyl acetate at 313.15 K and atmospheric pressure were obtained with use of the C80 isothermal mixing calorimeter (Setaram). The correlation of the data was carried out using the NRTL model and Redlich–Kister equation. A comparative analysis with the literature data on all available binary subsystems of the quaternary system was carried out. Other thermodynamic properties (C_(p,m)^E, S_m^E, ∆_mix S_m, G_m^E and ∆_mix G_m) of the binary systems were estimated using literature data and well-known formulas of classical thermodynamics.