Effects of attrition of bed material on the solid circulation rate in a recirculating fluidized bed (RCFB) were studied in detail. Effects of different operating and design parameters such as operation time, superficial velocity, bed inventory, particle size, and spacing between jet top and draft tube bottom on the solid circulation rate in terms of attrition were studied. A mathematical model was developed on the basis of experimental results to identify the effects of attrition of bed particles on the solid circulation rate incorporating the effects of the various operating and design parameters. To develop the model, dimensional analysis and nonlinear regression were used. The model equation was a nonlinear equation, which implies a relationship between the solid circulation rate and other operating and design parameters. The model equation can estimate the solid circulation rate over a range of operation time and other parameters. Decrease in solid circulation rate can be predicted with increasing operation time, using the model equation.