Higher Manganese Silicides (HMSs), consisting of two naturally abundant elements, show high oxidation resistance at high temperatures. These are thus of particular interest as potential p-type thermoelectric (TE) materials to be used at mid-temperature range. A typical HMS exhibits a maximum dimensionless figure of merit, ZT, around 800 K, but values ranges from 0.3 to 0.7, depending on whether the samples are single-, poly- or oriented-crystalline forms. Currently, several recommended reviews [1–3] are available but additional results have been obtained since these publications. In this chapter, we will review our current knowledge of the crystal and electronic structure, TE properties, and applications of HMSs.