In this study, the reaction of NF3 gas plasma with cobalt oxide (Co3O4) film grown on the Inconel base metal surface was investigated. Experimental results showed the plasma etching rate as high as 3.36m/min at 350 degrees C under 220W of plasma power with negative 300 DC bias voltage. AES and XPS analyses revealed that reaction product is CoF2, demonstrating that the plasma processing is a fluorination reaction. Based on the linear kinetics law, the activation energy of the etching reaction was derived to be 66.93kJ/mol. This study demonstrates that the plasma decontamination technique can be applied to efficiently and effectively remove radioactive surface contaminants such as Co-60 hiding in the oxide film on the surfaces of the metallic waste generated during decommissioning of old nuclear power plants.