The significant results of technology efforts directed by the NASA Lyndon B. Johnson Space Center investigating liquid oxygen/hydrocarbon (lox/HC) propellant combination are presented. These efforts are intended to identify viable propellant combinations and system designs to replace nitrogen tetroxide and monomethylhydrazine for future spacecraft orbital maneuvering and attitude control systems, and to date have been focused primarily on the various technology areas of lox/HC combustion - injector element design effects, performance, combustion chamber heat transfer, coking, and ignition. In addition, a study was performed to compare candidate lox/HC propulsion system concepts and to evaluate major system/component design options. The data generated provide quantitative substantiation of trends previously experienced with hypergolic propellants and with a lox and rocket propellant combination. More importantly, however, the data provide a sound footing for the technology data base that must be built to support future systems development.