Hydroxytyrosol (3,4-dihydroxyphenylethanol) is a phenolic compound obtained during olive processing in oil manufacturing. It plays a role in enhancing the oxidative stability of olive oil with positive effects on human health. The raising interest towards the use of natural antioxidants as stabilizers in polymer formulations makes hydroxytyrosol a potential candidate to substitute synthetic antioxidants in polyolefin formulations. In this study, hydroxytyrosol was compared in antioxidant efficiency with two other compounds, one of them obtained from natural resources (alpha-tocopherol) and a synthetic commercial phenolic antioxidant (Irganox (R) 1076). Chemiluminescence was used to as a tool to assess the increase in the polypropylene stability to thermo-oxidative degradation. A significant increase in the value of oxygen induction time with the initial concentration of natural antioxidants tested under isothermal conditions at 140, 150 and 160 degrees C was observed. A comparison at the same concentration level (0.1 wt %) between the three antioxidants showed an order of stabilizing efficiency as: alpha-tocopherol > Irganox (R) 1076 > hydroxytyrosol, but all them showed clearly their stabilization performance in polypropylene. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 3393-3399, 2011