A thermodynamic model for the partial oxidation of hydrogen sulfide (H2S) was used to study product compositions attainable in the superadiabatic partial oxidation regime. Superadiabatic partial oxidation techniques permit attainment of operating temperatures significantly in excess of the adiabatic temperature of the incoming reactants. The superadiabatic partial oxidation of H2S is studied numerically by varying acid gas and oxidizer feed compositions with overall goal of optimizing the hydrogen yield. These reactant parameters were varied as follows: (20% H2S/80% N-2)/air, (20% H2S/80% N-2)/O-2, 100% H2S/air, 100% H2S/O-2, (75% H2S/25% N-2)/air, and (75% H2S/25% N-2)/O-2. The performed analysis predicts favorable H-2 and low SO2 yields in the region of ultra-rich superadiabatic partial oxidation at equivalence ratios above 6 for all studied acid gas and oxidizer compositions. Pure oxygen as an oxidizer shifts the thermodynamic range to equivalence ratios >12. Oxygen operation appears thermodynamically promising. With oxygen, high H-2 and low SO2 yields are attainable in the superadiabatic systems with lower degrees of heat recuperation. (C) 2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.