Using coal-water slurry with fine coal of mean diameter 28 mum, the heat transfer coefficient at the annular outer wall of a double tube bubble column was determined based on measurement of the lateral temperature profile and heat transfer rate in the annular section. Heat transfer behavior of the slurry system without bubbling was similar to that of liquid single phase and, it was found that the heat transfer coefficient could be estimated by introducing the viscosity ratio of coal slurry to water into the estimation equation for a liquid single phase. In the gas-liquid and gas-slurry systems, the effect of gas holdup on the heat transfer is more remarkable than that of liquid or slurry velocity. Consequently, a major factor affecting the heat transfer at the annular wall for the gas-coal slurry is the gas holdup.