The thermal dissociation of hydrogen sulfide gives promise of becoming an economic method to convert a hazardous waste into valuable products, conserve fossil fuels, and increase usable reserves of fossil fuels. The dissociation rates at temperatures which are attractive for an industrial process are not well-characterized. We studied the dissociation of hydrogen sulfide into hydrogen and sulfur at temperatures from 1350 to 1600 K and pressures from 15 to 30 kPa in an alumina reactor. The rate depends on the surface-to-volume ratio of the reactor. The surface reaction is the dominant contributor; the activation energy for the forward surface reaction is 194 kJ/mol. We present a global rate expression that includes surface and gasphase contributions.