Corrosion is recognized as a serious problem in power plants that generate electricity. Many power plants generating a huge amount of electricity are needed to be taken care of it. Otherwise, these will cause a serious damage to human life. Corrosion gives rise to wastage of material in huge quantities, failure of tubes, leakage of tubes, sudden shutdowns as well as a reduction in the lifetime of components. Also, it reduces the thermal and electrical efficiency of a power plant to a maximum extent leading to minimum maintenance, outage, and replacement of cost. In understanding this problem, the present chapter illustrates the corrosions that take place in the power plants and preventive measures to be taken to avoid huge destruction to the life on the earth and to the environment. This, in turn, reduces the maintenance cost and damage to the human life.