Keywords: Thermal energy storage (TES) Sugar alcohol Galactitol Mannitol Eutectic mixture Phase change material (PCM) a b s t r a c t The thermophysical properties of mixtures of galactitol and mannitol were examined via differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD) analysis. The aforementioned sugars were found to form a eutectic mixture at a 30:70 molar ratio of galactitol and manntitol, and displayed a melting point of 153 °C while maintaining a high latent heat of fusion (DH fus = 292 J g À1). The XRD data revealed that the eutectic mixture contained the a, b, and d forms of mannitol with the d form being the major component. By varying the temperature ramp rates utilized in the DSC measurements from 0.5 °C min À1 to 20 °C min À1 , the heat of crystallization as well as the crystallization temperature increased (c.f., DH crys : 64 J g À1 ? 197 J g À1 ; T c : 68 °C ? 105 °C). In addition, the temperature and the enthalpy of crystallization were also improved by up to 34% through the addition of small quantities (up to 0.5 wt%) of nucleating agents, such as graphite powder or silver iodide. After 100 heating/cooling cycles under an atmosphere of nitrogen, the heat of fusion of the eutectic mixture decreased by only 4% with no change in the melting point, and the mixture appeared to be chemically stable according to a Fourier transform infrared (FT-IR) spectroscopic analysis. Collectively, these data indicate that the eutec-tic mixture exhibits excellent cyclic stability under ambient atmospheres and offers potential for use in thermal energy storage applications.