The stearic acid (SA) - hexanamide (HA) binary mixtures were prepared, and the phase diagram and Tammann plot were constructed. The differential scanning calorimetry results indicated that a eutectic composition formed by 46.2 mol% SA and 53.8 mol% HA melted at the temperature of 331.15 K with a latent heat of 176.62 J.g (-1). Fourier transform infrared spectroscopy and X-ray diffraction results revealed that SA and HA were just physical mixture. The results of thermogravimetric analysis and 100 thermal cycles test respectively manifested that eutectic mixture had good thermal stability and reliability. Therefore, eutectic mixture is promising for thermal energy storage application.