This report summarizes the work performed to develop and verify the design of a prototype molten carbonate fuel cell stack which meets the requirements of a 1990's - competitive, coal-fired, electrical utility central station, or industrual cogeneration power plant. The test of the 20-cell Subscale Stack No. 3 was terminated voluntarily following 5020 hours of operation. All of the objectives of the Test Plan were achieved. Design changes incorporated to improve electrolyte management, provide negative and cell short protection, and control stack height reduction were demonstrated to improve the stack operating capability. Variations in the in-plane thermal profile were evaluated. No cell performance decay resulted from the thermal transients. A stack disassembly and analysis plan is presented. The design of Subscale Stack No. 4 was completed. It includes a revised separator plate design, a one-piece cathode current collector, and a revised end plate design. It will be operated at conditions which ameliorate nickel oxide cathode dissolution. Sheet metal repeating-part hardware was completed for the stack. Full-area bubble barrier tape fabrication trials were conducted using the newly installed tape casting equipment. Modifications to the slip recipe were required to improve the homogeneity of the part. Tooling required to fabricate full-area separator plates for the full-area short stack was completed. Material and component tests evaluated the dimensional stability of anodes and cathodes. Anodes have demonstrated stability believed acceptable for stack testing. Corrosion testing of INCO 825 and AISI 310 stainless steel continued. 43 figs., 39 tabs.