Results of experimental measurements of solids mass flux profiles in a circulating fluidized bed riser over a wide range of operating condition are described. Three types of radial solids flux profiles are found to exist : parabolic/core-annular, radially uniform, and U-shaped. A model for these three regimes is proposed and correlations of two model parameters are obtained. A comparison of predicted solids flux profiles with experimental data is very promising. The correlations for the boundaries of the three regimes and the core radius for the core-annular regime are obtained.