Thermogravimetry at constant temperature and programmed temperatures is used to study reaction kinetics and possible mechanism of COS desulfurization using ferric oxide as the main active component. The apparent reaction activation energy is smaller in hydrogen atmosphere than in nitrogen. The desulfurization reaction of COS takes place easily in a hydrogen atmosphere. At the same time, the influence of the reducing temperature on the desulfurizing reaction was also studied in the TGA apparatus and was shown to play an important part for ferric desulfurization. The optimum temperature for the reducing reaction is under 360 degrees C. The kinetics of the COS removal reaction are approximately first-order. When the reaction gas contains hydrogen, the apparent reaction activation energy is 12.36 kJ mol (1), in contrast to 21.92 kJ mol (1) in the absence of hydrogen. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.