A theoretical model of the coal gasification with steam in a chemical moving bed reactor is developed. A very high temperature nuclear reactor provides the energy for accomplishing the endothermic gasification reactions. The model is developed in chemical regime giving information about the temperature profiles, the coal conversion and the specific productivity in the gasification process. For the heat transfer, the three resistances have been included (conduction, convection and radiation). The results have shown that the coal conversion in the heterogenic water "shift" reaction is smaller than the ones in mass transfer control. The gas velocity can change strongly the conversion, for velocities under 0.06 m/s, for bigger quantities the change is negligible. An increase in the gas temperature at the reactor input leads to an increase in the coal conversion; an increase in the temperature from 900 K to 1300 K increases the conversion 40%. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.