This article explains a laboratory procedure to produce an antioxidant from grinded, dehulled and partially defatted sunflower seeds. Initially, a solvent suitable to extract phenols was searched among different solutions of water mixed with ethanol, methanol and acetone at 40% (vol/vol) (each tested at pH 5, 7 and 9). Both the ethanol/water 60:40 (vol/vol) and the acetone/water 60:40 (vol/vol) mixtures proved to be suitable for the dephenolization of sunflower seed shells, but in the next steps of this research, the mixture ethanol/water 60:40 (vol/vol) at pH 5 was used. Secondly, the procedure to obtain the antioxidant product was defined, which consisted in hydrolysis of sunflower seed phenols with 1.25 N NaOH at room temperature for 60 min and finally the recovery of caffeic acid formed from chlorogenic acid with ethyl acetate. From 25 g of partially defatted sunflower shells, around 90mg of powdery antioxidant product, consisting of 58% caffeic acid, was obtained. The antioxidant product, the caffeic acid standard and propyl gallate were added to different edible fats at the same dose of 240 AU (antioxidant units) per kg fat. A Rancimat test, at 130 7C and an air flow of 20 L h21, demonstrated that the effectiveness of the sunflower antioxidant product was essentially similar to that of the caffeic acid standard, but 15–20% lower than that of propyl gallate. In conclusion, dephenolization of sunflower seeds could be economically convenient, not only because a useful antioxidant can be produced, but also because the raw material composition can be improved for other uses.