Nanoparticles of TiC and TiCN were synthesized by a magnesium thermal reduction process. The process was performed in the sequence of (1) the transfer of TiCl4+C2Cl4 solutions into a liquefied magnesium protected with Ar, (2) the magnesium reduction of metal chlorides, (3) the formation of a titanium carbide by the reaction of Ti and C atoms released by the magnesium reduction, and finally (4) the vacuum separation of the residual liquid Mg and MgCl2. Titanium carbonitride could be synthesized by maintaining the reaction chamber in nitrogen atmosphere. The average particle size of both TiC and TiCN synthesized was about 80 nm each. The composition of the TiC nanoparticles was approximately TiC0.95 with 0.9 wt % free carbon whereas that of the TiCN nanoparticles was TiC0.46~0.53N0.46~0.51 with 0.1 wt % free carbon.