In this paper there are listed the factors that determine corrosion, and described types of corrosion processes that the most often cause corrosion of power transformers tanks, as well as external and internal influences on their corrosion. The dynamics of corrosion processes is shown, with elaborated ways of anticorrosion protection throughout all phases since designing transformers, through technological processes of their tanks production, to maintenance during the transformer exploitation in outdoor or indoor space. Detailed preparation and corrosion protections procedures were developed that is now applied in Croatian and world wide practice, during the process of transformer tanks manufacturing, and also highlighted two dominant protection coating system, the conventional solvent-based, as well as widely used modern system of waterborne coatings protection. Finally is shown the real anticorrosion repaired tank of power transformer with 60 MVA, which was conducted in summer 2011, on Thermal Power Plant-Heating Plant in Zagreb (TE-TO Zagreb), in which is discussed regularly maintenance of exterior and interior tank surfaces, with determining the appearance of moisture in transformer oil. The operational plan for the implementation of mentioned transformer tank corrosion protection is defined, and described the preparation of external tank surfaces, then applying layers of solvent-based paint, as well as the final control of selected paint system application.