The vapor pressures of liquid [2-diethylaminoethylamine (2-DEEA) + n-heptane] mixtures were measured by a static method between T = (273.15 and 363.15) K at 10 K intervals. The excess molar enthalpies H(E) at 303.15 K were also measured. The molar excess Gibbs energies G(E) were obtained with Barker's method and fitted to the Redlich-Kister equation. The Wilson equation was also used. The molar excess Gibbs energies and the molar excess enthalpies were used to test the applicability of group-contribution models, including the modified UNIFAC model in the versions of Larsen and Gmehling and the Disquac model. Particularly, the proximity effect of N atoms was analyzed.