Desalination is a viable solution to the 21th century´s shortage of freshwater. The most widely used desalination processes are thermal and membrane. Other modern techniques apply solar and electrical energy for evaporation and electrodialysis. Many desalination plants (DP) are located in desertic/arid regions with a harsh climate and limited rainfall. About one-fifth of the DPs operate in the Middle East, with Saudi Arabia producing half of the world desalted water. The final selection of materials of construction for plant equipment must be a compromise between technological and economic factors. Corrosion problems and their solutions in several DPs in the Middle East, USA and Mexico are presented.