tIn this work, we present a thermodynamic characterization of the water + 1-alkanol mixtures, includ-ing the description of phase diagrams, interfacial tension and viscosities, by the soft-SAFT equationof state coupled with the Density Gradient Theory and the Free-Volume Theory. A molecular modelfor water and 1-alkanols is chosen within the soft-SAFT framework with particular attention to thehydrogen-bonding interactions. The cross-association parameters are, in most cases, predicted from theWolbach–Sandler rules, while the dispersive energy and segment diameter of the mixture are normallyfitted to an isotherm/isobar of one mixture and predicted for the rest. Quantitative agreement is found inall cases, with a single set of parameters able to simultaneously describe vapor–liquid and liquid–liquidequilibria. The interfacial tension of these systems is predicted using the Density Gradient Theory withoutusing any adjustment for the crossed influence parameter, finding good agreement with the experimen-tal data. Finally, the viscosity of water and several 1-alkanols is described by the Free-Volume Theory,using the density as an input taken from soft-SAFT. In particular, the viscosity of the water + methanol,water + ethanol and water + 1-propanol mixtures is described with two binary viscosity parameters inorder to quantitatively reproduce the viscosity maximum of those systems. The excellent agreementfound for all properties represents a step forward to the extension and implementation of molecular-based equations for the accurate design of processes involving these complex mixtures with very modestcomputational effort.