In the present work, sodium oxalate in the buffer solution was used to stabilize L-ascorbic acid in the aqueous media. The effect of sodium oxalate concentration on the stability of L-ascorbic acid was studied in the range of 0.0033 to 0.011 mol/dm3 in the presence of KH2PO4 (0.03 mol/dm3) and Na2HPO4 (8.99x10-4 mol/dm3). When the concentration is within the range of 0.0056 – 0.011 mol/dm3, solutions of L-ascorbic acid remain stable for at least 30 minutes at room temperature. Therefore, 0.0056 mol/dm3 sodium oxalate concentration was selected for further investigation