Co-electrospinning of fatty acid eutectics in the presence of nanoparticles has been used to produce thermally conductive nanofiber composites with suitable phase-transition temperature range. Capric acid (CA), palmitic acid (PA) and lauric acid (LA) and their eutectics were used as the phase change materials (PCMs) and polyethylene terephthalate (PET) was used as the supporting matrix. Four different nanoparticles (Al2O3, Fe2O3, SiO2 and ZnO) at different weight fractions were added to the fatty acid eutectic solutions which eventually appeared in the electrospun composites. The structure, morphology, thermal properties and energy storage capacity of the prepared nanocomposite-enhanced phase change materials (NEPCMs) were examined by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. The average diameter of nanocomposite fibers was found to be significantly smaller than that of pure composite fibers due to the increased conductivity in spin dope associated with the presence of nano particles. Also, the presence of nanoparticles has caused the phase transition temperature ranges (onset offset) of the composite fibers to shift towards lower temperatures (e.g. lower melting point temperatures). The fabricated PCM composite have shown proper thermal conductivity, energy storage capacity and efficiency as well as phase transition temperature range all of which are necessary for low temperature energy storage/retrieval systems.