This report describes the development of a downhole steam generator system for use in enhanced oil recovery. The system is composed of four major components: A state-of-the-art review indicated that advances in technology would be necessary in two areas (high pressure combustion and high temperature packer seals) in order to fabricate a field-worthy system. As a result, two tasks were undertaken which resulted in the development of a novel ceramic-lined combustor and a unique all-metal packer. These elements were incorporated into an overall system design. Key system components were built and tested in the laboratory. The program culminated in a successful simulated downhole test of the entire system, less tube string, at Sandia National Laboratories. 5 references, 41 figures, 9 tables.