(Solid + liquid) and (liquid + liquid) phase diagrams have been determined for (1-octanol, 1-nonanol, 1-decanol, or 1-undecanol + acetonitrile, propanenitrile, or butanenitrile) mixtures. Only mixtures with acetonitrile show immiscibility in the liquid phase with an upper critical solution temperature. The excess molar volumes (V-m(E)) have been determined for a 1-alkanol (1-octanol, 1-nonanol, 1-decanol, or 1-undecanol + propanenitrile) and (1-undecanol + butanenitrile) at 298.15 K and atmospheric pressure. For all the mixtures investigated in this work, the V-m(E) is small and positive. Mixtures were investigated in terms of the modified UNIFAC (MU) model using the interaction parameters cited in the literature. The model describes in the correct range of temperature and composition the liquidus curves, critical points, and excess molar enthalpies. The Extended Real Associated Solution (ERAS) and Flory-Benson-Treszczanowicz (FBT) models were also used to represent the V-m(E). data and to predict excess molar enthalpies of the investigated systems. Excess molar volumes and enthalpies (literature data) are well-represented by the ERAS model. The ERAS model gives the better prediction than that of the MU model for excess molar enthalpies. The calculated curves using ERAS are closer to the experimental points except in the region of low concentration in alcohol. This means that, in terms of ERAS, the contribution to the excess molar enthalpy from the self-association of the alcohol is overestimated. The MU model underestimates the excess molar enthalpy. The FBT model cannot be used to predict these data as the interaction of the unlike molecules is not described in this model.