A thin, solid-state membrane H2S electrochemical cell was developed and operated successfully at 150 degrees C and 138 kPa to produce liquid sulfur and hydrogen in electrolysis mode. Anode catalyst ruthenium (IV) oxide/p-dichlorobenzene/cesium hydrogen sulfate (CsHSO4)/platinum black is found stable and sustainable over a period of 8 h. Sulfur does not block anode catalyst sites during this sustainable period of operation. The H2S splitting process is enhanced with reduction in particle size of the CsHSO4 crystal. (C) 2008 The Electrochemical Society.