A differential scanning calorimeter (DSC) was used to determine binary solid + liquid-phase equilibria (SLE) for naphthalene + diamines NH2-(CH2),-NH2 (n = 6, 8, and 12) mixtures. The results obtained with this technique were compared with those predicted by the modified UNIFAC (Larsen and Gmehling) and ideal models. It was found out that all the systems are simple eutectic systems but there are deviations between experimental and predicted SLE.