This work focuses the investigation of factors impacting perchlorate ion formation in sodium hypochlorite solutions and the development of a predictive model for perchlorate ion formation by starting with a brief history of perchlorate ion as an emerging contaminant; a detailed summary of the analytical methods employed for analysis of perchlorate, bromate, chlorate, hypochlorite, and chlorite ions in various hypochlorite ion solutions; and planning of experiments to identify factors that impact perchlorate ion formation. A detailed discussion of the effects of hypochlorite and chlorate ions, ionic strength, and temperature is followed by the derivation of a simple expression that relates the effects of ionic strength and temperature on the second-order rate constant. The developed predictive expression was used with Bleach 2001 Predictive Model output to predict formation of perchlorate ion in various hypochlorite ion solutions. The application of the predictive expression was used to discuss potential formation of perchlorate ion and provide recommendations to minimize contamination of drinking water, when hypochlorite ion is used as a disinfectant.