Decarbonizing the global infrastructure for production of chemicals and energy by reducing or eliminating the use of fossil fuels is essential to mitigate the effects of anthropogenic climate change. One route to reducing CO 2 concentration in the atmosphere is through the use of carbon-negative sources of energy such as the incomplete combustion of biomass to produce hydrogen (H 2 ). This process encompasses numerous mature and industrially implemented biomass-to-hydrogen technologies, including fermentation, super critical water gasification, and steam reformation of pyrolysis-gasified hydrocarbons. The production of H 2 from biomass is particularly useful since H 2 can be used as both industrial feedstock and fuel. Despite the widespread availability of biomass, existing technologies for producing H 2 using biomass have not achieved large scale industrial adoption, and typically focused on high-quality and high-cost woody feedstocks. Currently, the vast majority of H 2 produced globally is from the steam reformation of hydrocarbons or coal (~68.6 million metric tons) or electrolysis (~1.4 million metric tons). This underutilization of biomass is due to a number of factors, but the single largest inhibitor is the prohibitively high cost of transportation. Among potential sources of biomass feedstocks, the estimated 137 million tons of available but unutilized carbonaceous material sent to municipal solid waste (MSW) annually in the US is particularly attractive because of the large amount of material concentrated in small locations. In practice, there are multiple challenges to the cost-effective production of H 2 from MSW and other available carbon-based waste products. Fermentation typically requires costly pre-treatment to purify the starting materials, while supercritical water gasification is energy-intensive and generally focused on valorizing landfill leachate. Due to low reaction rates with solid materials, gasification into small-molecule carbonaceous intermediates, known as syn-gas, can enable additional strategies including steam reformation followed by the water-gas shift reaction. Steam reformation and the water-gas shift reaction are typically coupled together in tandem, using catalysts and additional energy input to drive the high temperature and endothermic steam reformation reaction at reasonable rates. A key challenge is that typical steam reformation catalysts are easily poisoned by sulfur and other contaminants or deactivated through coking, necessitating the use of more expensive or pre-purified feedstocks and excess steam. The high sulfur content and inhomogeneous composition of MSW also limits its use for direct combustion as fuel, as the high cost of tail-gas cleanup is typically uneconomical unless subsidized. The aforementioned challenges motivate interest in development of alternative technologies to produce H 2 economically from these currently underutilized organic waste products. To circumvent the technical limitations of existing biomass-to-H 2 technologies as they relate to MSW, here we describe a multi-step thermo-electrochemical looping process using sulfur-intermediates that we propose may provide a viable route to economical carbon-negative H 2 generation. This process utilizes the unique ability of elemental S to rapidly dehydrogenate organic matter to generate H 2 S and sulfur-enriched biochar at the boiling point of S (444.6 °C). Rather than abstract H 2 from H 2 S directly (a method that has thus far eluded large-scale industrial implementation), H 2 S is used here as an indirect reducing agent to chemically regenerate SO 2 feedstock from H 2 SO 4 for use in an electrochemical SO 2 -depolarized cell.