The objectives of this study were to obtain fractions enriched in thymol by molecular distillation of oregano essential oil and to evaluate their antioxidant properties. In addition, this operation was modelled considering the effects of evaporation temperature and feeding flow on thymol concentration in the residue fractions by means of artificial neural networks (ANN). All residue fractions had a higher percentage of thymol than the distillates. The thymol composition in the residue fractions reached values up to 2.4-fold higher than in oregano essential oil. Higher concentrations of thymol produced lower values for IC50 according to DPPH. technique, indicating an increase in antioxidant properties. During the storage test, all the residue fractions analysed showed better peroxide, conjugated dienes and conjugated trienes values than distillates and OEO when they were used in sunflower oil samples. The results of storage stability showed that residues and BHT are very good antioxidants. The ANN created demonstrated good predictive ability for the operation of molecular distillation of oregano essential oil. (C) 2015 Elsevier B.V. All rights reserved.