Abstract Reactive Oxygen Species include molecules such as superoxide, peroxide and hydroxyl radicals. High levels of these molecules have been shown to lead to diseases such as heart disease, cancer, and neurodegenerative diseases. The proposal aims to determine if the reduction potential of the Rieske protein in Complex III can be a source of superoxide when the reduction potential is not matched its redox partner. In order to study this hypothesis, a yeast system where mutations can be made to Rieske has been produced, and a series of mutant yeast strains have been made. The production of superoxide will be measured using confocal microscopy and its effect on the yeast ascertained through growth assays. In addition, the reduction potential of the isolated yeast Rieske protein will be measured. The protein will also be thoroughly characterized, adding a new system that has not been explored previously to the literature.