The effect of bed temperature in the annulus region on gas bypassing from annulus to riser and solids circulation rate has been determined in an internally circulating fluidized bed. The bed voidage in the annulus region increases with increasing temperature. The average fractions of gas bypassing of annulus gas are 59.4% and 87% at room temperature and high temperature (400 degreesC to 800 degreesC), respectively. Solids circulation rate increases with increasing annulus gas velocity, but is nearly independent of riser velocity. Solids circulation rate increases with increasing temperature.