AbstractAlgeria has experienced over the past four decades, several periods of drought which led to the use of seawater desalination through a vast program initiated in 2003. The program is implemented to achieve 13 seawater desalination units, to produce 2.3 million m3/day in 2011, to meet needs for potable water, as well as those of small and medium industries in the coastal regions and neighboring regions. This capacity will reach 2.5 million m3/day in 2015, taking into account the tourism development in these regions. Because the program set up is based solely on fossil energy and that desalination technology is a major consumer of energy, to ensure sustainability of water resources and save the energy source (natural gas), it became necessary to initiate prospective studies to replace, for this purpose, fossil energy by other energy sources such as: renewable energy and nuclear energy. Currently, nuclear power is presented as a more attractive solution through the development and technological expertise recorded in the field of nuclear desalination integrated systems. Several demonstration units have been realized which have gained an undeniable know how. The experience accumulated in this area is estimated to 247 reactor-years. For this purpose, a study of nuclear desalination unit is performed for a potential site located in the Western Algerian coast, which is characterized by a very low rainfall rate of 400mm/year. This study is taken in the national context. Indeed, the energy sources outputs that are candidates in this study are based on the Indicative Program of Electricity Generation developed in Algeria. The outputs related to nuclear energy are in respect with the threshold fixed to 10% of the maximum power installed. The definition of nuclear desalination unit capacity is fixed to meet the water demand of the population of this region covering a period of 25 years beyond 2025.The cogeneration option is taken into account in this study. In this study, we present the economic evaluation results of coupling several nuclear reactors with two desalination processes MED and RO, using DEEP3.1 software. These results are compared with those obtained with fossil energy sources based on Natural Gas.