The reduction of barium sulfate to produce barium sulfide is a part of the two-step process for converting sulfur dioxide to elemental sulfur, described in Part I. This reaction was investigated using a thermogravimetric analysis technique with and without an impregnated nickel catalyst at reaction temperatures between 700 and 1050 degrees C. As an example of the reactivity of nickel-catalyzed barium sulfate powder, almost complete conversion was attained in about 3 min at 850 degrees C under a hydrogen partial pressure of 86.7 kPa. The Prout-Tompkins nucleation and growth kinetics equation was found to be useful for describing the rate of this reaction, which had an activation energy of 210 kJ/mol for fresh barium sulfate powder and 143 kJ/mol for fresh nickel-catalyzed barium sulfate powder. The reduction reaction of nickel-catalyzed barium sulfate powder is of order 0.6 with respect to hydrogen partial pressure. (c) 2006 Elsevier Ltd. All rights reserved.