Abstract: An objective procedure and technical study has been carried out that measure the degree of oxidation of vegetable oil samples stabilized with phenolic antioxidants. Traditionally used antioxidants were added with in the maximum permissible limit (200 ppm) and samples of refined, bleached and deodorized Soybean oil were stored at ambient conditions for a period of one year. Analysis was performed periodically after each sixty days. Various chemical and instrumental methods were applied to test the oil deterioration that permit the distinction of oxidative alteration level during storage. Quantitative measurements revealed significantly higher rate of oxidative alteration and degradation in untreated samples during the early period of six to seven months as compare to the stabilized and treated samples. Treated samples were found to show more extensive degradative changes in the ending period of four to five months as compare to early period.