Paper presents results of theoretical deliberations on the possibility to utilize energy deriving from high temperature nuclear reactors (HTR) to drive highly endothermic fossil fuels gasification by the assistance of carbon dioxide. Synthesis gas resulting in this process could be utilized for chemical syntheses e.g. to produce methanol or liquid synthetic fuels. At the same time practical implementation of such a process would make it possible to reduce carbon dioxide emissions to the atmosphere. This reduction would be realized in a twofold way: through a reduction of the amount of fuel burnt ( bituminous coal ) that is necessary to process execution as well as through utilization of carbon dioxide as a reaction substrate. Unfortunately the limit of such a solution has been relatively low temperature of the heating media coming out of the HTR reactors (< 800°C), which negatively influences on the gasification process equilibrium. In order to evaluate the economic feasibility of the process in question, the methodology to calculate the equilibrium composition of the synthesis gas was developed. It was assumed that coal gasification process takes place in two consecutive stages. They are referred to as: quick pyrolysis of the fuel associated with production of the after pyrolysis gas and carbonizate and consecutive gasification of the resulted carbonizate by means of the gasifying mixture of gases (CO₂, H₂O, O₂) and after pyrolytic gases. For such a system the chemical model was created that enables to calculate equilibrium composition of the after reaction gas mixture based on stoichiometric balance and on thermodynamic data. The methodology that was developed makes it possible to produce calculations for any species of coal with the application of mixture of carbon dioxide , steam, and oxygen at any proportions and excess in relation to the amount of the gasified coal. What is necessary is only knowledge of the basic physical and chemical characteristics of fuel and dependence of the after pyrolytic gases composition and pyrolysis intensity on temperature. In this paper the exemplary calculation results of the equilibrium composition in temperature range of 600-900°C are presented. This corresponds to temperature of the heating medium from the nuclear reactor HTR. Analysis of the influence of various factors (e.g. coal species, temperature, initial composition of the gasifying media) will enable the optimization of gasification process at an angle of oxygen consumption minimization and obtaining gases with high hydrogen concentration, or selection of coal with the best characteristics to low temperature gasification.