Low-temperature solid-oxide fuel cells. Lower temperature operation dramatically expands the applications of solid-oxide fuel cells (SOFCs) and provides the opportunity to incorporate a wider variety of materials in SOFC power generation systems with greater reliability and lower cost. This issue of MRS Bulletin highlights the potential of and progress toward operating SOFCs at low temperatures. The articles describe materials development and processing, the development of highly active electrodes and their 3D microstructural characterization, as well as the use of protonconducting electrolytes. The cover shows a low-temperature SOFC stack that is being commercialized by Redox Power Systems. The stack is built from a series of individual SOFCs with an interconnect and seal between each cell. A major advantage of the lower temperature operation is the ability to use conventional stainless steels for the interconnects and simple gasket materials for sealing. See the technical theme that begins on page 773.