The detailed kinetic mechanism of pyrolysis and oxidation of the H2S-CH4 mixture was developed. The mechanism was validated on experimental data on the ignition delay, laminar flame velocity, conversion degree of H2S and CH4, as well as on the yield of main conversion products - H-2 and CO. The developed mechanism was used for a numerical study of the conversion degree of H2S and CH4, the syngas yield and syngas composition during partial oxidation of the H2S-CH4 mixture with H2S/CH4 = 1/9, 1/4 and 3/1 in a plug flow reactor of 1 m in length in the wide range of initial temperature (T-0 = 600-1400 K) and fuel-to-air equivalence ratio (phi = 1-30). It is shown that the maximum relative yield of syngas can be obtained at phi = 3-5 depending on T-0 and the H2S/CH4 ratio in the fuel. The mole fraction of H-2 in syngas is higher than that of CO. For the mixture with H2S/CH4 = 3/1, the mole fraction of H-2 can be greater than the equilibrium value in a certain range of phi similar to 6-10. The reasons for this effect are analyzed. The mole fraction of CO in conversion products rapidly decreases with increasing phi. As a result, the ratio gamma H-2/gamma(CO) increases fast with the growth of phi. Besides H-2 and CO, the conversion products can contain S-2 and NO (at phi similar to 2), CS (at phi similar to 3), CS2 (at 3 < phi < 10), unburned hydrocarbons (at phi > 3) and other species. The least amount of conversion byproducts is observed at phi = 3-3.5 when there is the maximum syngas yield. Syngas selectivity turned out maximal at phi = 2.5-3. Therefore, phi similar to 3 seems to be the most optimal value for carrying out the conversion of H2S-CH4 mixtures. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.