Abstract:Oxygen fugacity quantifies the oxidizing and reducing capacity of a system, also reflects the oxygen partial pressure or escape ability. In geoscience, it is related with the valence state of redox- sensitive elements of rocks and minerals, and indicates their relative oxidability and reducibility. Rocks and minerals with the same composition under different oxygen fugacities might show contrastingly different physical and chemical properties. Therefore, it is of vital importance to accurately control and monitor oxygen fugacity in high- pressure and high- temperature experiments. This paper focuses on how to control and monitor oxygen fugacity in piston- cylinder and multi- anvil apparatus technically. First, the double- capsule technique, its principle, set- up configurations and experimental tips under hydrous and anhydrous systems which is well developed for controlling oxygen fugacity is introduced. Then redox sensor method including transition metal- solid solution and inert metal- solid solution which is used for monitoring oxygen fugacity is demonstrated next. Finally, the principle and set- up of oxygen solid electrolyte sensor method is exhibited, with some possible improvement raised up. Due to technical limitation, in- situ oxygen fugacity control and monitor in high- pressure apparatus are far from well- developed, which results in underestimation or even erroneous estimation of the influence of oxygen fugacity on physical and chemical properties of rocks and minerals. Therefore, development in control and monitor of oxygen fugacity in high- pressure apparatus is of great urgent and significance.