A new model has been developed to analyze the performance of a moving bed reactor producing uranium tetrafluoride. The model includes the solid and gas flow rates, heat transfer by convection, conduction and radiation between gas and solid streams and by the external surrounding. A kinetics model has been also developed for the gas-solid reactions on the basis of the grain model in which, the different resistances are taken into account to determine the overall reaction rates. This study provides an initial and theoretical basis for optimum design of the moving bed on the basis of the kinetics models. The optimum design is carried out from the viewpoint of required length of the reactor and the maximum conversion. According to the primary expectations which are provided by the kinetics models, the feed temperature seems not to have any effective influence on the reactor performance. On the other hand, it is predicted that the inlet gas flow rate contributes an important role. The investigations show that although the kinetics models are rather useful in primary estimations, the strong interdependence between different zones of the reactor may prevent general expressions. (C) 2010 Elsevier Ltd. All rights reserved.