The characteristics of the breakup process in supercritical spray is investigated during the injection of supercritical sulfur hexafluoride into dissimilar gases at supercritical pressures and subcritical temperature of the injected fluid. The visualization techniques used are backlighting and shadowgraph methods. The spray angles are measured and the breakup and mixing process are observed at near and supercritical conditions. The results show that spray angles are decreased with the in..ease of the ratio of density $(frac{ ho_f}{ ho_g})$. At the supercritical temperature, the spray angles in atomization region are kept nearly constant such as the typical spray angle in gas injection. The mixing process is changed radically at the temperature where $frac{d ho}{dT}=frac{1}{2}[frac{d ho}{dT}]_{max}$ at given pressure.