Salt brine electrolysis systems produce a solution that can contain up to 400 mg/L free available chlorine (FAC). These systems are very appealing to small utilities. The scientific literature contains numerous reports from utilities using electrolysis systems citing enhanced microbiological kill rates and lower THM levels than normally would be expected by disinfection with FAC alone. Researchers have speculated that the presence of minority oxidant species (ozone and/or chlorine dioxide) are responsible for the observed increased disinfection capability of salt brine electrolysis systems. If strong oxidants such as ozone and chlorine dioxide are present in electrolysis cell liquors, the chemical reactions that can occur are complicated both thermodynamically and kinetically. This paper describes analytical methods developed to identify reactive species and potential interferences in salt brine electrolysis cell anode liquors.