LG-Caltex Oil Corp. developed a 50 kW PAFC stack during 1994-1999. The aim of this study was the preparation of a 50 kW PAFC stack for the application of on-site power generation system. To manufacture the large-size electrodes (4225 cm 2), automated manufacturiner facilities were used. These facilities provided uniformity and reproducibility of manufacturing of the electrodes. These electrodes showed high current density (400 mA/cm(2) at 0.65 V) in the unit cell measurement. Only 3% of degradation of cell voltage was observed in the unit cell test over the cumulative operation of 6000 h. The 50 kW PAFC stack was composed of 109 unit cells and 19 cooling plates. The 50 kW stack showed 85% of hydrogen utilization rate and 40% of electrical efficiency (LHV). Uniform voltage distribution among cells (within 5%) was observed during operation. LG-Caltex Oil Corp. is developing the prototype 50 kW PAFC power generation system during the years 2000-2002. This prototype will be composed of reformer, inverter, stack and control systems. The prototype will be tested for the commercial application of on-site power generation. The long run, reliability and economic feasibility of the prototype will be analyzed for commercial power generation.