The thesis deals with the galvanic behaviour of two couples under the Arabian Gulf sea water conditions. These couples are: ( I ) Molybdenum containing stainless steels/Copper-base alloys and (II) Zinc/carbon steel The material covers variety of topics. These comprise a detailed survey of desalination plants regarding history, material selection, desalination techniques with an emphasis on evaporation (MSF and MEB distillation), production of distilled water economic aspects, corrosion assessment of different parts of the distillers and remedies for corrosion. The corrosion problems have been treated from a theoretical basis, including a literature survey and laboratory scale experimentation. The galvanic study of Case (I) identifying the effects of alloy type, temperature, cathode/anode area ratio, stagnation and stirring conditions on both the galvanic potentials and galvanic currents of the various couples. The results were interpreted in the context of the modern theory of corrosion. Conclusions and recommendations were given which are applicable to desalination plants. The study also included the evaluation of the Mo-stainless steels regarding their resistance to pitting and crevice corrosion. The results were quantified using their pitting resistance equivalent (PRE) values. The galvanic study of Case (II) involved the evaluation of the effects of the presence in the water of bicarbonate-, chloride-, sulphate-, nitrate ions, medium temperature, presence of metallic ions and aeration or deaeration on the efficiency of Zinc (as a sacrificial anode) in the couple Zinc/carbon steel. The results were treated as a zinc potential reversal phenomenon. This enabled the formulation of various conclusions that are applicable to zinc sacrificial anodes used in the cathodic protection systems of carbon steel water boxes of turbine oil condensers.