A chemo-biochemical process for desulfurization of simulated natural gas containing hydrogen sulfide (H2S) was investigated. The results showed that using polyurethane foam as a support for immobilization of Acidithiobacillus ferrooxidans obtained good biological oxidation performance and the maximum oxidation rate of ferrous iron was 4.12 kg m3 h1. Moreover, a semi-empirical formula was set up for calculating theoretical ferrous oxidation rate as a function of influent Fe2+ and Fe2+ concentration in the bioreactor. The integrated chemical and biological process achieved removal efficiencies of about 80% when treating high concentrations of H2S (15 000 +/- 100 ppmv). (c) 2012 Society of Chemical Industry