The problem under consideration is determination of temperature fields in a rock mass with a spherical cavity that is partly filled with a heated liquid. At that, the tendency to self-heating of the substance stored in the cavity leads to appearance of high-temperature fields, that in turn results in development of significant thermal stresses. Herewith, real physical and mechanical properties of the rock within the rock mass must be taken into consideration. So, the rock mass material is viewed through the lens of its inhomogeneity, which to a considerable extent is determined by temperature fields for any instant of hot fluid storage. Herewith, the temperature process is transient, but taking into consideration slow redistribution of the thermal field during a long period of time, the problem of its calculation can be considered as a quasi-steady-state problem. Temperature field around the cavity is calculated using an explicit difference scheme.