The invention relates to a method for producing magnetite with a purity of no less than 90% and higher than 98%, by oxidation of pulverized wustite (iron oxide), at temperatures ranging from 200° C. to 800° C., with the addition of water in liquid or steam form, in counter-current or concurrently, in an externally heated reaction chamber with a controlled atmosphere. The amount of water used to oxidize the wustite being 60 to 500 ml per kilogram of wustite, the grains of wustite powder are injected into the reaction chamber having a size no greater than 100 μm for optimal reaction.