Iron is the most abundant transition metal element within an organism and exhibits various physiological activities. Free iron in living cells is particularly important because of its high reactivity, suggesting a relationship to cellular damage or death. Free iron exists in its stable redox states, ferrous ion (Fe2+) and ferric ion (Fe3+). In living cells, research involving the behavior of Fe2+ is necessary to understand the intracellular reductive environment, metal transporters and water solubility of Fe2+. Mito-FerroGreen is a novel fluorescent probe for the detection of ferrous ion (Fe2+) in mitochondria where Fe-S clusters and heme proteins are synthesized, and enables live cell fluorescent imaging of intracellular Fe2+.Mito-FerroGreen is widely used in ferroptosis research, one of the various research fields Dojindo has a strong portfolio in. (https://www.dojindo.com/ferroptosis-detection-selection-guide/)