The Idaho National Laboratory (INL) is currently assessing the feasibility of using solid-oxide based electrolysis cell technology for high temperature electrolysis of steam for large-scale hydrogen production. In parallel, the INL is studying the simultaneous electrolysis of steam and carbon dioxide for syngas (hydrogen/carbon monoxide mixture) production. When linked to a nuclear power source, this technology provides a carbon neutral means of producing syngas while consuming CO(2). The scope of experimental investigations at the INL includes single button cell tests, multi-cell stacks, and multi-stack systems. Multi-cell stack testing used 10 cm x 10 cm (8 cm x 8 cm active area) or 20 cm x 20 cm (18 cm x 18 cm active area) planar cells supplied by Ceramatec, Inc (Salt Lake City, Utah, USA). Multi-stack testing encompassed up to 720 10 cm x 10 cm cells and was conducted in a newly developed 15 kW Integrated Laboratory Scale (ILS) test facility. Gas composition, operating voltage, and operating temperature were varied during testing. The tests were heavily instrumented, and outlet gas compositions were monitored with a gas chromatograph. Results to date show the process to be a promising technique for large-scale hydrogen and syngas production. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.