[en] A radiochemical method based on isotope dilution has been used for investigating the corrosion process in various aggressive agents. The corrosive effects of hydrochloric acid, sulphuric acid and nitric acid on steels 35M-16 and OT-60 as well as on cast iron FC-20 were investigated under various experimental conditions. The non-radioactive iron ions in the solution resulting from the anodic dissolution of the metal sample to be investigated act as internal diluent for the radioactive ⁵⁵+⁵⁹Fe³⁺ ions in the given corrosive system. The corrosion process has been described quantitatively by means of a kinetic parameter called the 'degree of resistivity of the metal sample to the aggressive agent'. (author)