Superoxide (O2-) is a free radical produced by the one-electron reduction of oxygen. It is produced as a side product of the reduction of oxygen to water, but also by immune cells as a chemical weapon to fight infection. There is evidence linking superoxide production to neurodegenerative diseases in humans. Among the methods of superoxide quantitation, the most reliable is by the reduction of cytochrome c. However, this method suffers from low sensitivity. To address this issue, we suggest attaching a fluorescent label, with fluorescence changing depending on the redox state of cytochrome c. As fluorescence is a much more sensitive spectroscopic method compared to absorbance measurements, we assume that the modified cytochrome c will afford better sensitivity in the detection of superoxide. A few mutations were introduced into cytochrome c; mutated as well as wild-type molecules will undergo spectroscopic studies in order to choose the best probe for superoxide detection. Then, fluorescently modified cytochrome c will be used in model and cellular superoxide-generating systems and the sensitivity of this approach will be compared with the absorbance measurements.