While the fuel cost has increased in the past years, the desalinated water demand has also increased sharply, especially in the deserted areas. The challenge is to be able to meet such future demand, minimizing the water production costs. The desalination concepts have evolved, achieving substantial progress: desalination thermal process is moving from MSF to MED, hybrids involving both thermal and membrane process are more and more implemented. Reduction in cost and the improved economics of desalination plants are essential elements for the development of communities. Energy, capital, and operating costs are key issues of water desalination economics. This will lead to an optimized process selection on a case by case approach: the choice will depend on the specific conditions prevailing on site, such as existing facilities, power and water demand increase, land availability, raw water quality, quality of water to be produced, ratio between power and water production, ratio between thermal and membrane desalination. The presentation will focus on these various aspects of seawater desalination economics.