Mesalazine is an anti-inflammatory drug used to treat inflammatory bowel diseases. It is structurally similar to salicylates and other nonsteroidal anti-inflammatory drugs, and is an active form of sulfasalazine. Indications for this drug are the treatment of acute exacerbations and maintenance of remission in Chron's disease and ulcerative colitis. In this thesis, the electroanalytic properties of mesalazine were investigated using cyclic and square-wave voltammetry techniques at different pH values of the basic electrolyte and using various surface modifications of glassy carbon electrode (GCE). The aim of the study was to investigate the electrochemical behavior of mesalazine using various nanomaterials as electrode surface modificators and to determine whether the obtained results can be used to develop a new analytical method for simultaneous determination of mesalazine and folic acid. By capturing cyclic and squarewave voltammograms, it was found that the pH value 6 of the base electrolyte, i.e., the Britton-Robinson R buffer is most favorable for the position of the mesalazine oxidation peak, which appears at a potential of about 0.25 V, with respect to the stability and voltammetric response of the folic acid. It was also found that the oxidation of mesalazine at this pH value is a reversible process. Furthermore, when modifying the surface of GCE with different nanomaterials, the best results were obtained by using a suspension of multi-walled carbon nanotubes functionalized with amino groups (MWCNT/NH2) in a solutin of 0.5% chitosan in 1% acetic acid. In addition, an important factor for the response of the electrode is the concentration of nanomaterials in the suspension applied to the surface of the electrode. The best signal with the lowest background noise was obtained by modifying the surface of GCE with suspension in which MWCNT/NH2 was at a concentration of 2 mg/mL, and further research recommends the use of this nanomaterial at said concentration as a GCE surface modifier with the most favorable effect on measurement outcomes.