This thesis describes development of a simple and efficient copper(I)-catalyzed cycloaddition reaction for the synthesis of 4-monosubstituted-1,2,3-triazoles from terminal acetylenes and hydrazoic acid (HN3). Hydrazoic acid was generated in situ from sodium azide and Brønsted acid. Reactions were preformed on small scale due to the hazardous nature of HN3. On the model reaction, employing phenylacetylene as a model substrate, the influence of different reaction parameters was examined. We optimized reaction conditions and found an appropriate acid for in situ generation of HN3, copper catalyst and its optimal amount, solvent, reaction temperature and reaction time for efficient cycloaddition reaction. The best results were obtained when employing sulphuric acid, copper(II) sulfate pentahydrate in combination with sodium ascorbate as catalytic system (CuSO4×5H2O/Na(asc)), reaction temperature 100 °C, reaction time 24 hours in tetrahydrofurane/water/ethanol solvent system. By employing developed catalytic system we prepared various 4-alkyl and 4-(hetero)aryl-1,2,3-triazoles. Melting points were determined to the prepared triazoles, which were characterised by using NMR spectroscopy and HRMS. Their purity was further analyzed by HPLC analysis.