During storage, walnut oil is extremely unstable. It is subject to physical and chemical changes with the accumulation on primary and secondary oxidation compounds. The present paper describes the fatty–acid composition of Reichert–Meissl (RM) and Polenske (P) fractions in different walnut oil samples stored at different temperatures in transparent and dark containers. The generally used but highly empirical RM and P values are considered to be a measure of the soluble and insoluble volatile fatty acids respectively, in vegetable oils. Both RM and P values were determined according to the methods of the association of Official Analytical Chemists, adjusted walnut oil at the Department of Food Technology UTM. In this context there are presented Specific Gravity and Refractive index at 25oC of walnut oil samples.