The process that we propose here begins with the reaction of organic feedstocks with S to produce H 2 S and C, along with CS 2 at higher temperatures. Figure shows the free energy and enthalpy of reactions between S and select carbon species likely to be present during the sulfur-reforming of biomass material to produce H 2 S and either C or CS 2 . At the boiling point of S, 444.6 °C, all reactions except the dehydrogenation of methane are endothermic, and all reaction except the oxidation of C are exergonic. These data indicate that at the boiling point of S, H 2 S and C are expected to be the primary reaction products when organic feedstocks are used. At higher temperatures, > 600 °C, all the reactions shown in figure are both exothermic and exergonic, such that CS 2 is expected to be a favorable reaction product. We note that in figure there is an apparent discontinuity between 500 and 700 °C; this discontinuity arises from different reference states of sulfur: S 8 for T < 900 K and S 2 at higher temperatures, consistent with the most stable allotrope at these temperatures. One challenge with the process described here is that at the boiling point of S, the reaction of S with cellulose and other organic materials produces a sulfur-rich carbon byproduct that likely has little or no economic value. Charcoal and cellulose feedstock yields a carbon-sulfur complex containing up to 40% by mass sulfur, while short-chain alkanes yield a sulfur-rich tar. Sulfur can be partially removed using inert gas or H 2 at temperatures of 700-1000 o C but significant amounts of S (~1-12 % by mass) are retained. Highly sulfurized biochar formed by reacting H 2 S with biochar has been proposed as a soil amendment for alkaline and sulfur-depleted soils, but otherwise has little value. If left unoxidized, this char could act as a long-term carbon sink, especially if biomass feedstocks are used. As the biomass itself removed carbon from the atmosphere during growth, this cycle may be carbon-negative if renewable energies are used. Alternatively, reaction at higher temperatures with gaseous S will convert the char into CS 2 which may be utilized via reaction 2b to generate more elemental S. Charcoal and other reduced forms of carbon (e.g., methane, methanol, ethane, and CO) has been previously used to generate CS 2 on both laboratory and industrial scale. The extra S produced through reaction 2b may then be used in reaction 3a to generate more SO 2 feedstock, thereby improving the final yield of H 2 per unit of biomass (reaction 1 verses reaction 2). However, this method will also produce significant quantities of CO 2 from carbon that would otherwise remain sequestered in sulfur-enriched char. Economic factors such as the cost of biomass and carbon-offset credits will likely determine whether this cycle produces carbon-negative H 2 or oxidizes the biochar to improve yields. Step 2: Catalytic Claus reaction