Boron Carbide is a ceramic material of technological application due to its extreme hardness and high chemical and thermal stability. The effect of synthesized boron carbide addition on pressureless sintering and hot-pressing of a commercial B4C was investigated. B4C synthesized by carbothermal reduction using carbon black as carbon source was mixtured in 10, 30 and 50 wt% to a commercial B4C. Powder mixtures were compacted into pellets and sintered by pressureless sintering at 2050 °C/30min Samples were compared to a pure commercial B4C and characterization results have not showed great differences. Relative densities of as-sintered materials exceed 93% of theoretical for all compositions and microhardness Hv of ∼ 32 GPa was obtained.