Nanocrystalline Cu50Ni50 alloy powder was prepared by the mechanical alloying process in high-energy planetary ball mill P7 under an argon atmosphere. Structural, microstructural, morphological, and magnetic properties were followed by X-ray diffraction, scanning electron microscopy coupled with EDX analysis, and vibrating sample magnetometry. The mixing of Cu and Ni powders at the atomic level leads to the formation, after 30 h of milling, of two fcc NiCu structures having crystallite sizes of about 15.6 and 65.9 nm and close lattice parameters of about 3.5783 and 3.5794 Å that would correspond to Ni 41.8Cu 58.1 (40.75 %) and Ni 40.6Cu 59.4 (59.25 %) compositions, respectively. Magnetic measurements reveal that the obtained powders are typical soft magnetic materials. According to the Mr/Ms ratio, the grains are either pseudo-single domain or multidomain. © 2017, Springer Science+Business Media New York.