The nanoencapsulation of quercetin, a strong antioxidant and radical scavenger, via methyl methacrylate miniemulsion polymerization, using miglyol 812 as costabilizer and lecithin as surfactant was studied and the effect of the monomer/co-stabilizer ratio and different types of initiator, 2,2'azobisisobutyronitrile (AIBN) and redox pair composed of hydrogen peroxide and ascorbic acid, was investigated. Reactions conducted in the presence of quercetin showed lower polymerization rates, indicating that the presence of quercetin inhibits (redox pair) and/or retards (AIBN) the polymerization reaction. The increment of the concentration of ascorbic acid in the reactions initiated by a redox pair resulted in a considerable increase of the reaction rate without influencing other properties as average particle diameter, due to the fact that ascorbic acid acts as a reducing agent minimizing the oxidation of quercetin. Higher quercetin recovery was obtained for nanocapsules when compared with nanospheres.