Square-shaped boron carbide ceramic composites have been produced by spark plasma sintering with the addition of 5 to 20 vol % titanium metal powder in the B 4 C matrix in order to initiate an in situ self-propagating high-temperature synthesis (SHS) of TiB 2 . The SHS reaction not only enhances many of the physical and mechanical properties of B 4 C, but also reduces the required sintering temperature and pressure because of the enthalpy of reaction between metallic Ti and B 4 C. Sintering has been carried out in the SPS-temperature range of 1450 to 1550 °C with a uniaxial pressure of 40 MPa and a dwell time of 4 min under a 1 atm argon atmosphere. The effects of various amounts of Ti additions and sintering temperature on the phase composition, density, hardness, fracture toughness, and microstructure are examined. X-ray diffraction and transmission electron microscopy evaluations have shown that added Ti completely transforms into TiB 2 , resulting in a core−shell microstructure with a carbon core, surrounded by a TiB 2 shell in the B 4 C matrix. Moreover, by carrying out a control experiment where TiB 2 was added instead of Ti, and performing a molecular dynamics simulation of the B 4 C-Ti interface, the significance of the in situ SHS process has been validated.