Chemical looping is a novel fuel conversion and material separation technology. It can be applied to obtain sulphur through selective oxidation of H 2 S. Further, chemical looping combustion (CLC) of sulphur can generate SO 2 with a high concentration without NO x formation. The high SO 2 concentration is adjustable and facilitates large-scale H 2 SO 4 production. In this study, we examined the thermodynamics of the CLC of sulphur for H 2 SO 4 production, which has not been reported previously. We analyzed the effects of reactor temperature and sulphur to Fe 2 O 3 oxygen carrier (OC) ratios on sulphur allotrope transformations and on the distributions of reaction products. Moreover, the reactors were operated auto-thermally. Based on this design, we examined the effects of fuel reactor (FR) and air reactor temperatures on the minimum recirculation of the OC, as well as the gas and solid products and heat released from the air reactor. Our results showed that the CLC of sulphur with Fe 2 O 3 OC could occur through an auto-thermal process. The FR in a sulphur CLC system should be operated over a temperature range of 800-950 C, with an Fe 2 O 3 OC recirculation between 45 and 143 kg/kg S(s) . Furthermore, when the FR was operated in the auto-thermal mode, we achieved 100% SO 2 conversion. The findings of this study may be applied to reactor design for large-scale H 2 SO 4 production through CLC of sulphur. K E Y W O R D S auto-thermal operation, chemical looping combustion, Fe 2 O 3 oxygen carrier, sulphur