The properties of hot atomic microimpurities (^57,58Co, ⁵⁴Mn) in cyclotron metallic targets were investigated using the reaction ⁵⁵Mn + α with emission Mossbauer spectroscopy employed to estimate the electronic state of the hot atoms. γ-Radiation self-absorption and sectioning methods were used to define the diffusion coefficients at 670-1200 K. The position of the ⁵⁷Co atoms in the manganese lattice after irradiation and subsequent heating at the temperature of polymorphic α → β manganese (1000 K) transformations was established. Rapid diffusion of cobalt atoms at the polymorphic α → β manganese transformation was revealed. The radiochemical behaviour of ^57,58Co, ⁵⁴Mn after target dissolution was studied. The conclusion arrived at is that hot impurity atoms are a very effective tool in investigations of metallic cyclotron targets.