In this paper, preparation of FeS nano-powder by high energy mechanical milling of Fe-S and FeS2-Fe powder mixtures was studied. Effect of NaCl as a process control agent on the progress of reactions, morphology of particles and magnetic properties was investigated. The structural evolution, morphology and magnetic properties of powders were evaluated using X-ray diffraction, field emission electron microscope and vibrating sample magnetometer. It was found that FeS formed after 15 h and 9 h milling of Fe-S and FeS2-Fe as starting materials, respectively. Addition of NaCl prolonged the process and changed the combustion reaction mechanism to gradual one in Fe-S mixture. It also reduced the mean particle size to 56 nm. Hysteresis parameter indicated the presence of different magnetic phases where antiferromagnetic phase was the dominant phase. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.