Various types of thermoelectric materials are required to find out optimum material solution to heat-waste conditions. In addition, lead-free materials are also favored for eco-material solutions, so that Pb-Te system must be replaced by non-hazardous material system. Less energy consumption for fabrication has to be also taken into account in material selection. In this paper, solid state processing is proposed to fabricate dense n-type semi-conductive, magnesium base thermoelectric materials. This approach is favored for low temperature fabrication of compounds and net-shaping to thermoelectric module elements. Mg-Si system is employed to describe the features of solid-state synthesis from the powder mixture of pure magnesium and silicon to Mg 2Si. Through measurement of its thermoelectric properties, the further possibility of this approach is discussed.