NASA has determined that it requires extremely durable, high-performance, low cost engines to meet future multi-use in-space, non-toxic, cryogenic propulsion requirements such as orbit transfer, descent, ascent and pulsing attitude control. Transpiration-cooling technology has long been considered a candidate for long-life thrust chambers but has never been deployed on a domestic rocket engine. In this program WASK Engineering, Inc. proposes to design, fabricate and hot-fire test a 100 lbf reaction control engine (RCEs) with transpiration-cooled thrust chambers and novel injector design. This effort will build on the technology demonstrations achieved on our Phase I program. These new transpiration-cooled O2/CH4 RCEs will be tested in existing atmospheric (non-vacuum) test facilities on an existing and operational test stand. Test results will be used to anchor and refine existing transpiration cooling thermal/performance analysis models. Ultimately, results of this Phase II program will lead to a durable, low cost, non-toxic RCE technology capable of using in situ propellant combinations, particularly oxygen/methane that will have higher performance than current toxic, expensive, storable hypergolic RCE designs using rhenium-based thrust chamber technology.