THIS PAPER IS A REVIEW of the State of the Art of the science and technology related to chemical and corrosion effects and behavior of steam with impurities. It is based on the industry experience, a review of literature and discussions with specialists from many industrialized countries. Briefly described is a new R&D project on Turbine Steam Chemistry and Corrosion aimed to advance the state of knowledge to a quantitative understanding of the phenomena involved in industrial steam applications. Of interest is the equilibrium and kinetic behavior of salts, bases, acids and gases; inorganic and organic, in superheated, saturated, and wet steam and water at moderate to high temperatures and pressures. The chemical properties which are being investigated include solubility in steam and water, volatility, chemical equilibria in the liquid phase, interaction with surfaces and condensation.