The main aim of this research is to fabricate the nano-crystalline Fe-Co-Si alloy to be used in producing soft magnetic composites. The alloy powders were prepared by using a planetary ball mill. Morphological, structural and thermal changes during milling were analyzed by scanning electron microscopy (SEM) coupled with EDX microanalysis, X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results confirm the production of the Fe(Co) and Fe(Co. Si) solid solutions after milling. Increasing the milling time has led to smaller crystallite sizes and lattice parameters, but larger amounts of micro-strain in the lattice. Prolonged milling has led to higher lattice parameters due to the segregation of solvent atoms to the grain boundaries. (C) 2012 Elsevier B.V. All rights reserved.