L – Ascorbic acid is a compound of great importance as it is vital to immune response and wound healing but it cannot be synthesised by some mammals, including humans. L- Ascorbic acid was also found to play an important role in the body as a free – radical scavenger, which may help to prevent free – radical induced diseases such as cancer and Parkinson’s disease. In foods, it is found in many fruits, especially in citrus fruits and berries, in vegetables and in beverages, especially those derived from fruit juices. Despite its wide presence in vegetables, many people do not acquire much Vitamin C this way. So very important is vitamin C. PI–50-1 model potentiostat, connected to Epsilon EC-2000-XP ( Ver.1,50,69_XP) programmer, and computer. The experiments were performed in a three-electrode cell, containing glassy carbon working electrode and counter-electrode (A = 0,07 cm2). Saturated Ag/AgCl reference electrode. All potential values reported refer to this reference electrode. The electrochemical oxidation of ascorbic acid at poly(N-methylaniline) modified electrode has been studied. The proposed mechanism explains the ability of poly(N-methylaniline) to electro-catalyze the anodic oxidation of ascorbic acid. It has been shown that poly(N-methylaniline) modified electrodes can be used for ascorbic acid assay within a pH range of 4,41 – 6,70, operating potential window of 0,25 – 0,4 V vs. Ag/AgCl, showing a linear range of response up to 1 mM, and a lower detection... [to full text]