The combination of different antioxidants involved in redox reactions can produce synergic effects (SE), which increase the food preservation effectiveness, reduce the amount of the food additives and can minimize/replace the use of synthetic antioxidants1. Ascorbic acid (AA) is one of the most studied natural antioxidants, while dihydroxyfumaric acid (DHF) has gained high interest in recent years, both by its plausible role in the “glyoxylate scenario” of primordial metabolism2 and as one of important participants of dicarbonic acids (Baroud') cycle3. The interaction of AA and DHF becomes naturally possible in fruits, e.g. grapes, where their presence has been reported3,4. In this study, the SE between AA and DHF has been investigated on the basis of UV-Vis and NMR spectroscopies data and by using DPPH (2,2-diphenyl-1-picrylhydrazyl) assay5. As a result of our studies, the synergic interaction of AA and DHF has been obviously demonstrated by the UV-Vis spectroscopy data. According to the 1H and 13C NMR data, no oxidation of DHF to diketosuccinic acid upon its reaction neither with DPPH, nor in combination with AA has been attested when deuterated acetone and methanol were used, while the DHF - triggered polymerization of acetone has been considered to take place, as a side-reaction, with the participation of methanol, on the basis of 2D NMR experiments6. In the mixture of deuterated solvents - chloroform and methanol the above-mentioned polymerization has not been attested. The obtained NMR data support the DHF decarboxylation to take place under the studied redox reactions. Further investigations are in progress in order to clarify the molecular mechanisms of the antioxidant and radical-scavenging activities of the mentioned antioxidants.