Hydrodynamics of an i-CFB (internal circulating fluidized bed) deNO(x) reactor has been studied by both experiments and modeling. Gas bypass was investigated by CO2 tracer method, and solid circulation rate was measured using an optical fibre probe at bed solid loadings of 33 kg and 2.275 kg. Radial profiles of bed voidage and solid velocity were discussed in detail. A hydrodynamic model was developed based on mass and pressure balances. Discharging coefficient C, was extracted from fitting the experimental data and an average value of 0.167 was taken for model simulation. The model could well capture the characteristics of the solid flow and gas flow distribution, and could serve as a useful tool for the design and simulation of the i-CFB deNO(x) reactor system. (C) 2013 Elsevier B.V. All rights reserved.