With the rapid growth in industries and urbanization toxic ions are discharged into rivers and other water bodies. Perchlorate, nitrate, chromate, thiocyanate, fluoride are toxic in nature if their concentration is more than permissible limit. Elimination of these toxic ions from water or waste water is of prime importance to reduce contamination of water bodies. The ion exchange process is found to be more effective among other treatment processes because of high selectivity, high mechanical and chemical stability of ion exchangers and low cost of regeneration. In this book important research findings of selectivity study of perchlorate and nitrate and adsorption of toxic hexavalent chromium, thiocyanate, fluoride from water and water-mixed solvent media using ion exchangers at different temperatures are highlighted.