A model for solids concentration and two phase pressure drop in the riser of circulating fluidised bed is proposed. It is based on slip velocity and takes into consideration buoyancy effects, hindrance effects and the formation of particle agglomerates. The local and average pressure drop and solids concentration were measured in a circulating fluidised bed for Geldart A and B group materials: a wide range of phase velocities and particle characteristics was covered. The experimental data of the present work and those reported in literature were compared with the predictions obtained by the model.