The supermalloy (Ni79Fe16Mo5) nanostructured powder with average crystallite size of about 8 nm was prepared by high energy milling. The obtained powders were characterized by X-ray diffraction, scanning electron microscopy, differential scanning calorimetry and vibration sample magnetometer. The results showed that the coercivity and the saturation magnetization reach about 8 Oe and 75 emu/g at 96 h and become approximately 1 Oe and 85 emu/g after a suitable heat treatment, respectively. The magnetic measurements confirmed that the supermalloy soft magnetic nanostructure powder was produced by mechanical alloying followed by a post heat treatment. The results revealed that a small amount of Mo element remain in the system up to 96 h due to (i) high fusion temperature, T-f = 2893 K, (ii) high mechanical hardness, (iii) low solubility of Mo into Ni at low temperatures in mechanical alloying conditions. (C) 2013 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.