The project will focus on identifying a sensor design and materials for use in measuring chromium vapor content under SOFC operating conditions. Auburn University will design, fabricate, and test a solid electrolyte based potentiometric chromium sensor. The sensor will use well-established solid electrolyte materials, such as yttria stabilized zirconia and beta alumina, with new auxiliary electrode materials to provide the sensitivity to chromium-containing gas species. Solid electrolyte based sensors have demonstrated excellent stability in aggressive environments, including measuring oxygen content in molten steel and in automotive exhaust gas, and are anticipated to provide the long-term stability required to monitor the conditions in SOFCs, potentially throughout their operational lifetimes. The sensor is being designed so that is can be integrated with a chromium capture system for the SOFC balance of plant to monitor state of the system.