This report documents the status of the US Department of Energy's Fuel Cells Program as of the end of FY 85. The report consists of (1) an overview of the Fuel Cells Program including a brief discussion of how fuel cells work; (2) a synopsis of the Phosphoric Acid Fuel Cell (PAFC), Molten Carbonate Fuel Cell (MCFC), and Solid Oxide Fuel Cell (SOFC) Programs and their 1985 projects; (3) a discussion of the Fuel Cells Advanced Research and Technology Development (AR and TD) Program and projects; and (4) a summary of the Fuel Cells Systems and Applications Program. A common direction of fuel cell development has been to combine individual cells into groups called ''stacks''or ''modules''in order to increase power output. In 1985, the scale-up of PAFC stacks to the 40-kW level continued, and a project involving the manufacturing of 46 power plants was completed. SOFC scale-up proceeded to the 24-cell submodule stage. An MCFC 1-ft/sup 2/ stack demonstrated effective management of electrolyte, control of end-cell shorting, and resistance of separator plates to corrosion during 4000 hours of operation. AR and TD provided information on reaction mechanisms and materials for MCFC's, SOFC's, and PAFC's. Systems and Applications development provided engineering and economic guidelines for MCFC's, SOFC's, and PAFC's, when used in a variety of utility and industrial settings. 3 refs., 32 figs., 4 tabs.