Cyclones can be used for heating solid particles where the direct contact with the gas is permitted. Since cyclones have potential applications as heat exchangers in fertilizer, polymer powder, pharmaceutical and other industries, study of cyclone as heat exchanger is deemed important. Experiments on air-solid heat transfer were carried out in a cyclone heat exchanger of inside diameter, using sand. The effects of solid feed rate , cyclone inlet air velocity , and four average particle sizes on the heat transfer rate, exit solid temperature, and heat transfer coefficient have been studied. An empirical correlation has been proposed for the prediction of heat transfer coefficients based on the present experimental data. The proposed correlation predicts the heat transfer coefficients with an error of for the present data and within an error of for the data of other investigators.