This paper is a contribution to the theoretical and quantitative understanding of the processes for the production of magnesium metal by metallothermic process in vacuum (Pidgeon Process). In the present study, effects of reductant type and amount were investigated. CaC2 is a low-cost alternative to FeSi (ferrosilicon) which is the common reductant in the Pidgeon Process. CaC2 slightly decreases the Mg recovery ratios but it remarkably decreases the process cost. The experimental study, conducted with the change of mass % FeSi-CaC2 ratio at 1,250 degrees C for 360 min, the optimum Mg recovery was measured as 94.7% at 20% CaC2 addition. Also aluminum, as a reductant, allows conducting the process at lower temperatures than that of FeSi. For the experiments conducted with Al addition, the highest Mg recovery ratio was measured as 88.0% in the conditions for 300 min process duration and 100% stoichiometric Al addition at 1,200 degrees C.