Phase diagram of benzamide-benzoic acid system has been studied by the thaw-melt method. Linear velocities of crystallization of the components and the eutectic mixture were determined at different undercoolings. Values of the heat of fusion were obtained from DSC studies. Excess Gibbs free energy, excess enthalpy and excess entropy of mixing were calculated. In order to know the nature of interaction between the two components, FT-IR spectral analyses were done. In addition to these studies, computer simulation has been done to obtain an idea about the interaction energy and the optimized geometry of the eutectic mixture. Microstructural studies showed the formation of an irregular structure in the eutectic mixture, which changed with aging and on addition of impurities. (c) 2008 Elsevier B.V. All rights reserved.