A facile method has been developed to fabricate nano-encapsulated paraffin wax within silica shell (SNsPCM) by in-situ hydrolysis and polycondensation of silica precursor. SNsPCM composite was studied using field-effect scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), X-ray Diffractometry (XRD), Raman and Fourier transformation infrared spectroscopy (FT-IR), respectively. The results revealed the formation of spherical paraffin nano-structure encapsulated within the shell of SiO2 with diameters ranging from 100 to 200 nm. Thermal stability, determined by differential scanning calorimeter (DSC), and thermogravimetric analyser (TGA), confirm the fabrication of a solid-solid and solid-liquid phase changing nanomaterial (PCnM). Simulations performed for thermal change within the paraffin core bounded by silica shell, for cycles of heating and cooling show excellent pressure durability of silica shell. PCnM behaviour studied using DSC measurement shows reversible fusion and solidification for repeated heating and cooling cycles. The SNsPCM composite with a paraffin encapsulation ratio of 79.89 wt% melted at 54.72 degrees C with a latent heat of 149.29 J/g and solidified at 52.09 degrees C with a latent heat of 100.16 J/g. The TGA results show improved thermal stability with an increased encapsulation ratio of PCnM by silica shell. SNsPCM can a potential material for thermal energy storage. (c) 2020 Elsevier Ltd. All rights reserved.