Polychlorinated biphenyls (PCBs) are one of the eradication compound lists of Stockholm convention. Korea started to analyze the PCBs concentration in high-voltage transformers in June 2004 and is developing PCBs disposing technology. As most of the transformers in Korea were contaminated at very low level of less than 5 ppm, it was decided that SCWO (supercritical water oxidation) process is suitable to treat them. The destroying parameters of SCWO process including optimum process temperature, pressure, residence time, and amount of oxidant were studied with a bench-scale facility. Based on these results and simulation, a pilot plant was designed and built to confirm the suggested condition. Recently detail design of a commercial plant was completed based on these results. In this paper, the procedures to scale up the design from a bench-scale facility to a commercial plant and major check points in each stage are introduced. (C) 2011 Elsevier B.V. All rights reserved.