In an attempt to enhance phase transformation and homogenization of Mn-doped FeSi 2 , mechanical alloying of elemental powders was applied. Cold pressing and sintering in vacuum were carried out to produce a dense microstructure, and then isothermal annealing was employed to induce a phase transformation to the β - FeSi 2 semiconductor. Phase transitions in this alloy system during the process were investigated by using XRD, EDS and SEM. As-milled powders after 100 h of milling were shown to be metastable state. As-sintered iron silicides consisted of untransformed mixture of α - Fe 2 Si 5 and ε -FeSi phases. β - FeSi 2 phase transformation was induced by subsequent isothermal annealing at 830 ? C , and near single phase of β - FeSi 2 was obtained after 24 h of annealing. Thermoelectric properties in terms of Seebeck coefficient, and electrical conductivity were evaluated and correlated with phase transformation. Seebeck coefficient electrical resistivity and hardness increased with increasing annealing time due to β phase transformation.