Magnetite Fe3O4 ultrafine powder, a magnetic material, was synthesized by a novel arc discharge method of metallic iron filaments in NaCl electrolyte. The size and shape of the products were influenced by the voltage between the two metallic iron filaments. Ultrafine iron oxides are important materials for magnetic and pigment applications. As a conventional magnetic material, nanocrystalline Fe3O4 powders with a spinel structure have potential applications for ferrofluid, magnetic refrigeration, bioprocessing, and information storage. Various methods of preparing iron oxide ultrafine powders have attracted attention, such as spray pyrolysis, forced hydrolysis, the oxidation-reduction reaction of ferrous hydroxide, microwave irradiation of ferrous hydroxide, combustion of iron(III) nitrate, microemulsion technique, and hydrothermal preparation technique. The paper reports a novel arc discharge method developed to synthesize magnetite Fe3O4 ultrafine powders. Compared to previous techniques for synthesizing Fe3O4, this method has many advantages, such as simpler operation, cheaper experimental precursor, and higher production capacity. The experimental apparatus used. A 50 Hz alternating-current power supply was used. The electrolyte in a 100 ml beaker contains 1 mol l−1 NaCl. Two metallic iron filaments were used as electrodes. The end of one electrode was fixed in the electrolyte, and the end of the other electrode was periodically placed in contact momentarily with the electrolyte's surface. The XRD patterns of the samples prepared by the novel arc discharge process at different voltage values between the two electrodes: 200, 150, 100, and 50 V, respectively. All the peaks were indexed as pure magnetite phase (spinal structure Fe3O4). After refinement, the lattice constant (a = 0.8408 nm) was about the same as reported (a = 0.8398 nm) in the literature. If you are looking for high quality, high purity, and cost-effective Fe3O4, or if you require the latest price of Fe3O4, please feel free to email contact mis-asia.