Chemically modified vegetable oils are biodegradable and eco-friendly particularly in comparison to petroleum transformer lubricant and insulating oils. These advantages motivate us to investigate the use of soybean, sunflower and cook waste. vegetable oils as suitable transformer oil alternatives. It is crucial to compare its physicochemical and electrical properties to those of transformer mineral oil to the American Standard Technical Methods (ASTM) specification to confirm its appropriateness. In This Study soybean, sunflower and cook waste oils undergo a two-step chemical modification by trans-esterification reaction with ethyl alcohol and potassium hydroxide as catalyst at 60 ᵒ C followed by epoxidation reaction with hydrogen peroxide and glacial acetic acid in amberlite IR – 120 resins. The physiochemical and electrical properties of synthesized bio-transformer oils were examined without the presence of tert butyl hydro quinone (TBHQ) as antioxidant and after applying oxidation conditions with the addition of TBHQ using approved methods. The chemical parameters that are measured include acid value, water content and oxidation stability. The physical characteristics that were tested were density, dynamic viscosity at 40 °C and flash point, breakdown voltage is the electrical property that was measured. Most of the data showed that the different characteristics properties of the ethyl ester of various vegetable oils meet the standard ASTM values after the addition of 2 grams of TBHQ antioxidant. Epoxidation of ethyl vegetable oil an improvement in the physico– chemical and electrical properties occurred with and without TBHQ antioxidant, Consequently, it can be used as a substitute for traditional transformer oil because it complies with most ASTM standard requirements.