The production of hydroperoxides and acetaldehyde and the kinetics of the oxidation process involving ellagitannins using model solutions containing ethanol (10% vol.), tartaric acid, iron, and copper were analyzed. Influence of oak phenolic compounds on wine aging in barrels under continuous-slow-oxidation conditions was also studied. Ellagitannins are revealed as impressive oxidation regulators, quickly absorbing the dissolved oxygen and facilitating the hydroperoxidation of wine constituents. This reaction induced tannin/anthocyanin condensation via acetaldehyde, favoring stabilization and deepening the crimson color; the limited oxidation of wine phenolic compounds prevented the development of brick-yellow color. In addition, the structure of the wine tannins was modified, reducing their astringency because of a higher polymerization level. Preliminary results on how ellagitannins affect the oxidation process of red wines are presented.