Sea water desalination methods are widely used. Thermal process and membrane process are the commonly used methods .However, both thermal and membrane processes are faced scaling trend. In this study, a new approach for the management of sea water and capture of CO2, where ammoniated sea water is reacted with carbon dioxide, has been investigated. The effects of reaction temperature, reaction time, and excess ammonia were assessed. The experimental results indicated that the optimum reaction temperature was about 20 °C and the optimum NH3H2O used amount was 4.8g/200ml. The results indicated that the new approach can reduce the sea water hardness and at the same time, contribute to reducing CO2 emissions.