A successful field test of the DEEP STEAM technology has been conducted. A direct contact steam generator was operated in the Kern River reservoir in cooperation with Chevron USA. The objectives of the test were demonstration of long term operation of a downhole steam generator, investigation of reservoir response, and the environmental consequences of the technology. The test was extensively instrumented to provide data on generator performance and reservoir response. The results show that the system is capable of long term operation in the oil field. It was demonstrated that substantial environmental improvements over surface steam production can be expected from injection of combustion products with steam in the downhole steam concept. The reservoir character was not altered by the test injection and appeared the same as that for pure steam injection.