Air injection is currently being evaluated as an IOR process for a wide variety of reservoirs. When applied in deep, high pressure, low permeability reservoirs containing high gravity crudes, the process is generally known as High Pressure Air Injection (HPAI). This paper will review the key factors that should be understood when considering the application of HPAI and it will describe the laboratory tests that are used to evaluate the “burning” characteristics of a candidate reservoir.