Additive Manufacturing (AM) boasts advantages over traditional (subtractive) manufacturing for non-mass-produced parts, namely material and cost savings and the ability to create geometrically complex designs. Refractory alloys, while highly desirable for aerospace applications for their high temperature strength, were initially designed to be manufactured via traditional methods. Although these materials have excellent mechanical performance, extreme temperatures vastly increase the oxidation of refractory alloys. To increase adoption of AM in this space, a new methodology must be developed to perform mechanical testing at high temperatures and limit oxidation. To perform the tests at high temperatures in an inert atmosphere (vacuum), a thermomechanical simulator was used, but required modifications to the hardware and testing environment. The thermomechanical simulator is capable of rapid heating rates via joule heating. An auxiliary system was used to reduce oxidation in conjunction with oxide capturing mechanisms within the vacuum chamber. The chamber and grips that hold the samples required modifications to withstand the higher temperatures. New grips and samples were designed using CAD and FEA software. Additional design challenges include build chamber limitations, minimizing powder consumption, and microstructural changes within the samples based on supports, build orientation, and welding parameters. The primary alloys that were examined are tungsten, molybdenum, and C103. This study serves to discuss the development of a rapid high temperature testing procedure for refractory alloys and analyze the elevated-temperature mechanical performance and oxidation.