A simplified mathematical model has been developed to estimate the particle flow rate in a spouted bed. It is based on the mass and momentum conservation laws in the spout region, and on the force balance in the annulus. Then the friction between particles and the vessel wall are considered in addition to the gravity and drag forces. The model equations are solved numerically, and the predicted values of the particle velocities and particle mass flow rates are compared with the authors＇ previous experimental results with reasonable agreement.