Amoxicillin is a commonly used antibiotic that is effective against various bacterial infections. However, due to its widespread use and poor biodegradability, it frequently occurs as a contaminant in aquatic ecosystems entering them through municipal or industrial wastewater. The aim of this study was to investigate the biosorption potential of buckwheat hull biochar functionalized with H₂SO₄ for the removal of amoxicillin from model solutions and synthetic wastewater. Characterization of the biosorbent was performed, including determination of the point of zero charge (pHpzc), functional group analysis by Fourier transform infrared spectroscopy (FT-IR) and specific surface area analysis (BET). Batch biosorption experiments were performed to investigate the efficiency of amoxicillin removal as a function of biosorbent concentration (1 - 10 g dm-3), contact time (15 - 360 minutes), initial concentration of amoxicillin (5 - 100 mg dm-3) and pH (2 - 12). The possibility of desorption of amoxicillin from the biosorbent using different solvents was also investigated. The optimal conditions for the biosorption process were as follows: pH of the solution = 6, biosorption time of 3 hours and biosorbent concentration of 8 g dm-3. An increase in the initial concentration of amoxicillin led to a decrease in the percentage of amoxicillin removal. A higher percentage of amoxicillin removal, and thus greater removal efficiency, was achieved when the biosorption process was performed in synthetic wastewater with added amoxicillin (from 47% to 95%), compared to the process in a model amoxicillin solution (from 17% to 49%). The biosorption process was slightly better described by the Freundlich model than by the Langmuir model. Of the three kinetic models used in the study (pseudo-firstorder, pseudo-second-order and Elovich model), the pseudo-first-order model described the biosorption kinetics best. The desorption of amoxicillin from the saturated modified biochar was most effective when a citric acid solution (2%) was used.