This report addresses the fourth logical unit of work of a multiyear program whose overall objective is the development of a gas-cooled phosphoric acid fuel cell (PAFC) for electric utility power plant application. This PAFC Technology Development Program continuation is structured to build upon the current cell technology baseline so as to advance critical component technologies to meet the performance, endurance, reliability and cost goals associated with successful energy service. The primary technical objectives are: Demonstrate performance endurance of current cell technology in 10-cell stacks at 70 psia, 190/degree/C, and 267 mA/cm/sup 2/. Select and utilize materials, procedures, and methods that improve cell degradation rate to less than 8 mV/1000 hours. Develop cost effective criteria, processes, and design configurations for stack components. Develop design configuration for multiple stack unit and a single 100 kW size fuel cell stack and attain performance goals. Develop design configuration for a 375 kW fuel cell module and demonstrate by test the average cell beginning-of-use performance objectives. Manufacture four 375 kW fuel cell modules and establish performance characteristics and interactions with other systems in a 1.5 MW pilot power plant. Progress is described. 4 figs., 9 tabs.