Dihydrorhodamine 6G is the reduced form of rhodamine 6G, which is used as fluorescent mitochondrial dye. It is nonfluorescent, but it readily enters most of the cells and is oxidized by oxidative species or by cellular redox systems to the fluorescent rhodamine 6G that accumulates in mitochondrial membranes. Dihydrorhodamine 6G is useful for detecting reactive oxygen species (ROS) including superoxide.