In the steelmaking process, the behavior of the top blown oxygen jet is an important factor for controlling BOF or EAF operation. Because the temperature in the BOF is very high, jet behavior is still not fully understood. In this study, supersonic oxygen jet behavior in a high-temperature field was investigated by measuring the velocity and temperature of the oxygen jet in a heated furnace, and the results were compared with a jet model proposed by previous researchers. The results showed that velocity attenuation of the jet was restrained and the potential core length was extended in a high-temperature field. Under these experimental conditions, the results were in good agreement with the jet model using Pr=0.715 and Sc=0.708 proposed by Kleinstein. Supersonic jet behavior for SCOPE-JET nozzle, which can be applied in EAF operation to obtain high-energy efficiency, was also investigated. SCOPE-JET had a long potential core and attenuation of the jet in the axial direction was extremely restrained. It was shown to be possible to obtain the jet behavior of SCOPE-JET nozzle using the jet model with the adiabatic flame temperature as the ambient temperature and appropriate temperature attenuation behavior in the axial direction.