Heat transfer characteristics between the immersed heater and the fluidized bed have been investigated in the riser of a three-phase circulation fluidized bed (0.102 m ID 3.5 m in height). Effects of gas (0.01-0.07 m/s) and liquid velocities (0-0.31 m/s) and solid circulating rate (2-8 kg/m(2)s) on the temperature difference fluctuations between the immersed heater and the bed, and thus on the heat transfer coefficients have been examined. The temperature difference fluctuation signals have been measured at a steady state and interpreted in terms of the standard deviation. The heat transfer coefficient and standard deviation of temperature fluctuations have increased with increasing gas velocity or solid circulating rate, however, the standard deviation has decreased while the heat transfer coefficient has not changed considerably, with increasing liquid velocity. The heat transfer coefficient has been well correlated in terms of gas and liquid velocities and solid circulation rate.