In spite of being known for centuries, iron oxides are still important. Such modifications as magnetite Fe3O4and epsilon phase ε-Fe2O3are of great scientific and practical interest due to their promising electromagnetic properties. nonetheless, only few methods allow synthesizing both of these phases, but they have some well-known disadvantages, which limit the possibility of using them widely. This work shows a unique method of synthesizing these materials in one shortduration plasma dynamic process using a coaxial magnetoplasma accelerator with iron electrode system. The plasma chemical reaction occurs between the iron-containing plasma and gaseous precursor (oxygen). The influence of oxygen pressure on the products of plasma dynamic synthesis was also studied in the framework of this investigation. It was found that the higher oxygen concentration leads to the formation of product with predominant content of epsilon iron oxide ε- Fe2O3, as well as lower oxygen concentration results in obtaining the product with the dominance of magnetite phase.