In this paper, temperature behaviour of an energy storage material (monochloroacetic acid) confined in a spherical capsule has been predicted. Nowadays, energy storage uses in many industries such as storing energy in low power consumption hours and use it in the peak of energy consumption, storing the waste energy in different industries and reuse it and different kind of usage in solar energy storage. Therefore monochloroacetic acid was used because of having a suitable melting point for solar energy storage systems. Finite element method, that is one of the numerical methods, was used in this paper. For validating of this model, the results were compared with an experimental data. Calculated correlation coefficient was 0.9907 that shows an acceptable precision.