The various simulant materials (non-porotype material) have been used to study the severe accident phenomena in a nuclear reactor by melt coolability technique. The present material can be used as a simulant material to study the thermal phenomena and heat transfer of a nuclear reactor accident scenario. The study of thermophysical properties plays a crucial role in the prediction of actual phenomena that occurred in a nuclear severe accident. This work devoted to analysing the effect of soaking time on thermophysical properties of non-prototype material CaO-Fe2O3 (21C79F; C = CaO, F = Fe2O3; 21:79 by wt. %). In continuation, an effort has been made to validate the simulation properties of the material in the context of other existing materials that are used for predictive analysis during a nuclear severe accident. A binary mixture powder of non-eutectic material CaO-Fe2O3 (21:79 by wt. % confirmed by phase diagram) in the form of cylindrical pellets is heat-treated at 1100 °C for one, two, and three hours of soaking time and further ground to powder form and finally, the heat-treated powder were analysed through characterization techniques to evaluate the changes in thermal properties, crystalline structure, and morphology. The results were also compared with the initial powder sample accordingly. The properties of material revealed that the material is thermally stable and it can be used in molten form to investigate the severe accident phenomena. The properties of CaO-Fe2O3 (21C79F) is possibly near to the properties of corium (a liquid mixture of UO2 and steel) and also environment-friendly as well as for human beings.