A laboratory-scale electrochemical cell was used for desulfurization of a synthetic fuel gas process stream containing up to 3000 ppm H2S. The cell was run at typical gasifier temperatures (600-650degreesC) and ambient pressure. The removal rate of H2S can be limited either by gaseous diffusion from the fuel stream to the cathode-electrolyte interface or by liquid diffusion of sulfur ions through the electrolytic membrane, depending on operating conditions (i.e., temperature and H2S concentration) and cell design (such as membrane thickness, membrane tortuosity, and flow channel design). For a 200 mL/min gas flow with a composition of 34.14% CO, 22.16% CO2, 35.13% H-2, 8.51% H2O, and 1200 ppm H2S at 600degreesC, the rate of H2S removal was determined to be limited by diffusion of sulfide ions through a porous membrane with a thickness of 0.9 mm, a porosity of 38%, and a tortuosity of 3.8. The cell achieved removal fluxes on the order of 1.1 3 x 10(-6) g mol H2S min(-1) cm(-2) at 650degreesC. While Y0.9Ca0.1FeO3 cathode offered adequate stability and conductivity to study the system at temperatures up to 700degreesC, the long-term cathode stability is still under investigation.