Boron carbide is a remarkable material among those with high hardness. This work presents the results obtained after sintering a commercial B4C powder with C+B2O3+Al2O3 and Ni Ti, Ni+Ti, used as sintering aids. The effects of sintering aids on several parameters as sintering temperature, phase formation, microstructure, fracture toughness (K-ic) and microhardness (H-v) sire also studied.