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Electrochemical oxidation of H2S to give sulfur and water was achieved at 900~ using fuel cells possessing the general configuration H2S, anode electrocatalyst/( 8 stabilized ZrO2 /La Sr Mn ~ /Pt, 02 (air) w/o Y208 or 5 w/o CaO) / 0.89 0.11 ,-'8 where anode electrocatalysts experimentally investigated for promoting the subject oxidation reaction included WS2 and the thiospinels CuNi~S4, CuC02S,, CuFe2S,, NiCozS4, and NiFe2S4. The predominant oxidizable electroactive species present in the fuel cell anode compartment was suggested to be hydrogen originating from the initial thermal dissociation of H2S (H2S ~ H2 + 1/2 $2) at fuel cell operating temperatures. Rapid anode kinetics were found for the anodic reaction with the empirical trend for exchange currents (io) per geometric area being found to be: NiFe2S, > WS2 > CuC02S4 > CuFe2S, NiCo2S4 > CuNi2S,.Currently, large quantities of hydrogen sulfide are generated as a by-product from both coal gasification/liquifaction and heavy oil desulfurization processes. These sources currently constitute greater than 50% of sulfur pro-* Electrochemical Society Active Member. duced in the United States per year. Sulfur removal during coal gasification is achieved using the well-established Claus process (1) where H2S is partially oxidized by air to give unit activity sulfur and water. The overall chemical reaction which occurs at 525~176 can be summarized as follows

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A high temp. reversible calcium oxygen cell has been developed that utilizes stabilized zirconia as solid electrolyte and a CaSi alloy immersed into a binary molten salt as the negative electroactive material (see scheme).