Bulk boron carbide is a promising high temperature thermoelectric material for power generation. Due to its unique rhombohedral crystal structure, boron carbide exhibits unusual properties such as high temperature stability, high Seebeck coefficient and electrical conductivity, and relatively low thermal conductivity at higher temperatures. However, the figure-of-merit (ZT) value of bulk boron carbide is still low, preventing its wide commercial applications. Recently, boron carbide nanowires with higher-predicted ZT values were synthesized. But their rational synthesis, that requires understanding of the growth mechanisms, is not fully realized yet. To solve the issue, we have started extensive Transmission Electron Microscopy-based cross-sectional examination of boron carbide nanowires. In this presentation, obtained experimental results and proposed growth mechanisms will be discussed. The results help to controlled synthesis of boron carbide nanowires with desired thermoelectric properties.