It is evident that nowadays materials with phase or chemical transformations are significantly considered to be in surpassing demand in the society being used for accumulating thermal energy. Furthermore, this usage leads to the process of increasing accumulated thermal energy per unit mass concentration to be achieved in a much beneficial and reliable manner. In comparison to these materials, well-known and widely–used solid and liquid ones are mainly associated with productivity and efficiencylosses. One of the methods, having desirable attributes for substantial enhancement in the energy productivity of phase change materials is proved to be the addition of solid nanoparticles with a large coefficient of thermal conductivity. This work focuses on numerical and experimental investigation the influence of nanoparticles of various materials and sizes on the processes of thermal energy storage in paraffin. In particular, the proceeding data of the thermophysical properties of paraffin with nanoparticles as being found by the optical spectroscopy method. Moreover, due to comprehensive results in experimental and numerical studies, the heat accumulating capacity of the phase change materials, as well as the dynamics and profile of the melting boundary around cylindrical heat sources were reported to be determined. Besides, the comparison of heatstorage capacity for phase change materials with and without nanoparticles is managed.