Abstract: A simple and rapid method for determination of ascorbic acid (I) was developed by combining an FIA system with an enzyme reactor (L-ascorbate oxidase), an inactive reactor and an amperometric detector. If a sample containing I and another oxidizable substance are 1st passed through the inactive reactor both of them will be detected at +0.7 V. If the same sample is then passed over the enzyme reactor ascorbic acid is oxidized enzymatically and the detector detects only the other oxidizable substance. The difference of the signals is proportional to the concentration. of the I. In juices and lemonades 4.1/20.2 mg/L were found. Pharmaceutical preparations contained 20-497.2 mg/tablet. The relative standard deviation was 0.9-11.7%. (SFS)