Hydrogeochemical prospecting consists of study of changes in the chemical composition of ground and surface waters caused by oxidizing ore bodies. Ground waters provide an effective prospecting medium as they reflect potentially large sample areas and deep subsurface zones.Waters near sulphide deposits are often enriched in trace metal and major element components. The free sulphuric acid and metal sulphates formed from oxidation of sulphides lower the pH of the water and cause considerable changes in their composition. This book discusses the methodology of large-scale hydrogeochemical prospecting for locating the potentially promising sulphide mineralization zones in four areas in Southern Sinai. To achieve such an objective, chemical analyses of water in conjunction with geomorphic, geologic and hydrogeologic evidence are used.