This slide presentation outlines information on the effects of temperature and source water quality on microcystin chlorination. Research objectives included: conducting a detailed evaluation of the inactivation kinetics of extracellular microcystin-LR by free chlorine at chlorine to microcystin molar ratios representative of water treatment practice (1,500-150,000); determing the effects of temperature, water quality, pH, chlorine dose, microcystin-LR concentration, on the rate of inactivation were evaluated; and, developing CT values for inactivation of extracellular microcystin- LR by free chlorine (C=residual disinfectant concentration, T= detention time).