Chemical looping combustion (CLC) is a promising technology for fuel conversion with inherent carbon capture. Because sulfur is an integral part of coal, the existence of sulfur contaminants in coal may degrade the purity of CO2 and deteriorate the performance of the oxygen carrier in the CLC process. To uncouple the complex behavior of inorganic sulfur in coal, sulfur release of three inorganic sulfur-containing compounds (FeS2, FeSO4, and CaSO4) mixed with activated carbon during the temperature-programmed process and the CLC process using iron ore as an oxygen carrier were investigated in a batch fluidized bed reactor at 950 degrees C. The results showed that, in the temperature-programmed process, the initial decomposition temperatures of FeS2, FeSO4, and CaSO4 were about 400, 500, and 650 degrees C, respectively. During the reduction and oxidation stages of CLC, SO2 was the main sulfur-containing gaseous compound. The sulfur stability of CaSO4 was higher than those of FeS2 and FeSO4. The fractions of sulfur converted to gaseous species in the reduction stage (X-S,X-g,X-red) of FeS2 and FeSO4 reached 90.38 and 87.42%, respectively, within 20.5 min, while the corresponding value was 53.97% for CaSO4. During 5 cyclic redox experiments at 950 degrees C, the fraction of sulfur converted to gas species was almost maintained stable, while the energy-dispersive X-ray spectroscopy analysis showed the accumulation of sulfur after the cyclic reaction.