This study focuses on the preparation of capric acid/stearic acid mixture as novel phase change material for latent heat thermal energy storage and determination of its thermal properties and thermal reliability by using differential scanning calorimetry analysis technique. The differential scanning calorimetry results indicated that the capric acid/stearic acid mixture with eutectic composition (83/17 wt%) was suitable phase change material for latent heat thermal energy storage applications in terms of phase change temperatures (T-m: 24.68 degrees C; T-f: 24.71 degrees C) and latent heat capacities (Delta H-m: 178.64 J/g; Delta H-f: 178.86 J/g). Accelerated thermal cycling test showed that the changes in phase change temperatures and the latent heats of the phase change material with increasing thermal cycling number were irregular. The probable reason of the changes in thermal properties of the phase change material with thermal cycling were also investigated using Fourier transform infrared spectroscopy method. Based on all results, it was concluded that thermal properties and long term thermal reliability of the prepared capric acid/stearic acid mixture makes it potential phase change material for heating and cooling purposes using a latent heat thermal energy storage system.