Peanut skin is a waste of industrial peanut butter that contains bioactive compound, which is used as antioxidant, anti-diabetic, anti-cancer, and anti-inflammatory. Supercritical carbon dioxide (SC-CO2) extraction as green technology is applied to extract peanut skin oil. The aim of this study is to optimize the operational conditions of pressure, temperature, and percentage of co-solvent to obtain oil yield and diffusivity coefficient. Determination of diffusivity coefficient was needed to evaluate the mass transfer between solvent and solute. The operational conditions of SC-CO2 studied were different pressure (10, 20, 30 MPa), different temperature (40, 55, 70 C and different co-solvent percentage (2.5, 5, and 7.5%(Vethanol/Vsolvent)). The extraction time was 3 hours respectively. The optimum condition were 29.95 MPa, 40 C and 6.49%(Vethanol/Vsolvent) with 14.95% yield and 8.47 E-12 m2/s diffusivity coefficient.