Isothermal vapor-liquid equilibrium (VLE) data are reported for the binary systems methanol + 2,2'-diethanolamine and water + 2,2'-diethanolamine and for the ternary system methanol + 2,2'-diethanolamine + water. Moreover, excess enthalpies (H-E) were measured for both binary systems with 2,2'-diethanolamine. The data were measured by means of a computer operated static apparatus and isothermal flow calorimetry, respectively. For the pure component 2,2'-diethanolamine, also vapor pressure data were measured using the dynamic ebulliometric method. The experimental binary data were correlated using linear or even quadratic temperature-dependent NRTL interaction parameters. The ternary data were used to validate the capability of g(E) models such as NRTL for the prediction of multicomponent mixtures on the basis of binary information.