AbstractThe capture of sulphur via the H2S‐CaO reaction during gasification of delayed coke has been investigated in a 6.4 cm dia. semi‐batch stirred bed reactor. Calcines from one of three limestones or a dolomite were mixed with coke which was then gasified in a steam‐nitrogen mixture at atmospheric pressure and 930°C. The H2S content of the gas, and the sulphur content of the sorbent were determined as functions of time. The effects of sorbent surface area, percentage calcination, and the Ca/S ratio on the extent of sulphur capture and the conversion of sorbents were determined. The sulphidation reaction was analyzed using continuous and grain models. After an initial stage of chemical control the reaction appears to be controlled by diffusion through the product layer of the