Caffeic acid is a natural polyphenol, occurring in many fruits and vegetables, especially in coffee beans, being the most representative compound among the hidroxycinnamic acids present in food. Since early nineties, it has been reported CA ability to act as an anti-inflammatory inhibitor of LDL oxidation and to chelate a range of metal ions. All these properties are common to antioxidant agents, and it might be of interest to investigate CA's ability to prevent ROS generation from Fenton reactions. The present work demonstrates that CA efficiently inhibits Fe (II)-mediated oxidative damage to 2-deoxyribose (2-DR) and that the inhibition is pH dependent. This effect may be related to CA's ability to chelate iron, specially at higher pH (7.2 HEPES/MES buffered media), in which deprotonated forms of its polyphenolic groups may chelate Fe (II) more efficiently therefore preventing the occurrence of Fenton reactions. Studies employing higher concentrations of 2-DR could also point to a scavenger activity in addition to suppression of oxidative damage by chelation. Further studies showed that CA is not capable to inhibit 2-DR damage from Fenton reaction when mediated by Fe (III). This difference in CA ability to chelate Fe (II) and Fe (III) could be demonstrated by UV-visible absorption spectrometry. In spite of CA antioxidant character demonstrated in the Fenton reaction at 37 ^oC mentioned above, a pro-oxidant behavior of CA was noted when reactions were incubated at 98 °C in presence of Fe (II). This unexpected result could be connected to structural damage to CA with production of oxidant species. These results may be of relevance in explaining the overall behavior of phenolic acids related to oxyradical reactions. Acknowledgments: Antonieta Alencastro (UnB), Prof. Dra. Isa G. J. Avelar (UnB), CNPq and Projeto Milenio-Redoxoma.