Regenerable mixed metal oxide sorbents are prime candidates for the removal of hydrogen sulfide (a major pollutant) from the hot coal gas in the simplified integrated gasification combined cycle processes. As part of this sulfur removal process development, reactor models are needed for scale-up. It is essential for this work to apply a reliable and simple modeling correlation for the conversion rate of zinc sulfide or oxygen in the regeneration reaction. The fit of such a model, assuming uniform conversion of the ZnS, was obtained from ambient pressure thermogravimetric analyzer test data with sulfided zinc titanate samples. An activation energy of about 140 kJ/ mol was obtained for the regeneration reaction rate constant.