The dissolution kinetics of vanadium trioxide in sulphuric acid-oxygen medium was examined. It was determined that the concentration of sulphuric acid and stirring speed above 800 r min 1 did not significantly affect vanadium extraction. The dissolution rate increased with increasing temperature and oxygen partial pressure, but decreased with increasing particle size. The dissolution kinetics was controlled by the chemical reaction at the surface with the estimated activation energy of 43.46 kJ·mol-1. The leaching mechanism was confirmed by characterizing vanadium trioxide and the dissolution residue using SEM-EDS analysis. Combined with thermodynamic calculation, the pressure leaching of vanadium trioxide in the temperature range (100 to 140 ℃) studied occurs as follows: V2O3 + O2 + H2SO4 = (VO2)2SO4 + H2O. The dissolution kinetics of vanadium trioxide in sulphuric acid-oxygen medium was examined. It was determined that the concentration of sulphuric acid and stirring speed above 800 r min 1 did not significantly affect vanadium extraction. The dissolution rate increased with increasing temperature and oxygen partial pressure , but decreased with increasing particle size. The dissolution kinetics was controlled by the chemical reaction at the surface with the estimated activation energy of 43.46 kJ · mol -1. The leaching mechanism was confirmed by characterizing vanadium trioxide and the dissolution residue using SEM-EDS combined with thermodynamic calculation, the pressure leaching of vanadium trioxide in the temperature range (100 to 140 ° C), studied as follows: V2O3 + O2 + H2SO4 = (VO2) 2SO4 + H2O.