Hydrodynamics of a gas-solid rotating bed reactor (RBR) in static geometry are investigated. Tangential injection of a gas at mass flow rate of 0.4-1 kg/s in a cylindrical vessel with a diameter of 0.54 m generates a rotating gas phase flow field. Introduction of solid particles in this field results into an annular dense gas-solid rotating bed. A stable annular gas-solid rotating bed without solids particles loss is achieved over a wide range of operating conditions. Goal of the presented work is to investigate, by means of experiments, the window for a stable operation of the gas-solid RBR, as a function of the solid particle diameter and density, the geometry of the RBR and the gas flow rate. If the solid particle diameter is comparable to tangential gas injection slot width, the establishment of a stable flow is delayed due to an increased slugging tendency. The upper limit of the solids content is found to decrease with decreasing solid particle diameter. Obtained experimental cold flow results are the initial steps in assessing the potentials of a RBR as an efficient gas-solid processing reactor from a process intensification point of view. (C) 2010 Elsevier B.V. All rights reserved.