In polyphenols redox systems, the solvent plays a fundamental role in the chemical behaviour of these compounds. Antioxidants can react in different ways with the prooxidant molecules. We have found differences in the antioxidant capacity of flavonoids such as naringin, neohesperidin, neoericitrin, hesperidin, narirutin didymin and the related flavones naringenin, hesperetin eriodictyol and isosakuatenin, when they are in the presence of radicals and solved in water or in an alcohol mixture.