The catalytic properties of Fe-MCM-41 and other iron-based catalyst materials for sulfur dioxide oxidation in highly concentrated gases have been characterized for the first time. Independent of whether the catalysts were synthesized by incipient wetness impregnation, solid-state impregnation, or in situ synthesis, the activity is found to be substantially higher than that observed for an industrial iron-on-silica reference catalyst. Although some activity is lost during the formation of the catalysts, Fe-MCM-41 catalysts are remarkably stable at temperatures of up to 1023 K. Fe-MCM-41 catalysts appear to be efficient for the conversion of highly concentrated gases that cannot be processed by conventional vanadiumbased catalysts due to thermal breakdown.