A review of works on the investigations of structural and phase transformations that occur in iron during its mechanical disintegration in the presence of liquid organic media. It is shown that the mechanoactivation of metals in the presence of organic media leads to the formation of a nanocrystalline structure of complex phase composition which is determined by the chemical nature of the milling medium and can include (in different proportions) α-Fe, amorphous phases, carbides, oxides, etc. By varying the composition of the medium, the duration of milling, and the temperature of a subsequent heat treatment, it is possible to obtain nanocrystalline systems with different structural and phase composition, dispersity, and thermal, magnetic and corrosive properties. It has been shown that for the investigation of processes that take place in nanocrystalline materials, it is necessary to use, apart from methods of analysis of the composition and structure of substances at the mesoscopic level (electron microscopy, X-ray diffraction, etc.), also methods which give information at the level of local atomic environment. In this work, Mössbauer spectroscopy was used for the systems on the basis of iron.