The study of the regularities of dissolution of iron group metals is practically significant in solving topical issues related to the optimization of technological processes of leaching and enrichment of iron-oxide ores, with corrosion of steel products, etching of surface oxides, dimensional processing of iron alloys. Existing ideas about the mechanisms of dissolution are largely hypothetical and require experimental confirmation, and the available publications are not sufficiently studied in detail. The paper presents the results of investigation of the mechanism of dissolution of Fe3O4 oxide in an acidic environment. Kinetic parameters (specific dissolution rate, reaction order for the H+-ion) were calculated. The dependence of the composition of formed iron adsorption complexes on the concentration of H2SO4 is established. Modeling of the process shows the effect on the kinetics of dissolution of iron hydroxo-and sulfate-complexes. The obtained data can be taken into account when studying the kinetic characteristics of iron group metals and used in practical applications to optimize processes related to the dissolution of iron in acidic environments. © 2020, Ore and Metals Publishing house. All rights reserved.