Refractory high entropy alloys (RHEAs) are promising materials for extreme environment applications, such as high-temperatures (> 1000 degrees C), corrosion and irradiation. In this study, a new CrMoTaTiV RHEA system has been designed using CALPHAD modeling and thermophysical parameter optimization, and produced by vacuum arc melting. Microstructure at room temperature as well as microstructural stability and me-chanical properties at high temperature have been investigated. It has been found that BCC alloys are formed with dendritic structures in which interdendritic regions are enriched with Ti, V and Cr, and de-pleted with Ta and Mo. Transmission electron microscopy analysis has shown dislocation tangles, loops and networks as well as the formation of nano-grains some of which are determined to be Ti-rich FCC phases. Besides, there is a secondary BCC formation below 1000 degrees C together with a Ti-rich FCC phase without any HCP or intermetallic phase formation. High strength and ductility of this alloy at the temperatures up to 1000 degrees C compared to the other RHEA systems have been attributed to its unique microstructure. This clearly shows the promise of this alloy system for high temperature applications due to its stability, high strength and possible oxidation resistance.(c) 2022 Elsevier B.V. All rights reserved.