The research documented here is a systematic study of the effects of pressure on the air-injection process for light oils in an adiabatic combustion tube. Tests were conducted at pressures up to 5400 psig. The purpose of this research is to study prospects of enhancing oil rates and recoveries by air injection, with particular application to large high-pressure reservoirs in remote locations where conventional injectants are not available. It was learned that air injection is applicable as a light-oil recovery process. In-situ combustion performance of light oils at high pressure is quite different from heavy-oil, low-pressure in-situ combustion (extensively documented in the existing literature(1,2)). Flue-gas generation and oil-displacement characteristics were excellent at all pressures for all oils. The primary effect of pressure on these series of tests was that higher injection rates were required as pressure increased. Air/fuel ratio was fairly constant with pressure, but air requirement varied with pressure, oil and sand. Significant process improvements were obtained when using reservoir sand for testing. Results from a tertiary test (conducted after waterflooding) were similar to those from secondary testing.