In this research, near fully dense single phase bulk multicomponent transition metal nitride (Nb1/3Ta1/3Ti1/3)N1-delta has been successfully synthesized from mixed commercial powders of NbN, TaN and TiN via reaction flash sintering technique. This was performed with an applied pressure of similar to 35 MPa at 25 degrees C under a constant DC electric field (similar to 24-32 V/cm). The flash event, which is the abrupt increase in current (up to similar to 25.2 A/mm(2)) and temperature, occurred without preheating. The threshold power dissipation on the sample right before the flash is similar to 0.7 W/mm(3). The formation of single phase (Nb1/3Ta1/3Ti1/3)N1-delta random solid solution and its compositional uniformity were confirmed by XRD and EDS, respectively. The effects of ball milling duration and limiting current density on phase formation were studied. Simulation based on Joule heating provides an estimate of the ultimate sample temperature of similar to 1850 degrees C. Vickers hardness of the obtained (Nb1/3Ta1/3Ti1/3)N1-delta is 17.6 +/- 0.6 GPa, which is comparable to similarly flash sintered ingredient binary nitrides of TaN and NbN. TGA in air shows that the oxidation resistance of (Nb1/3Ta1/3Ti1/3)N1-delta is better than that of TaN and NbN but inferior to TiN. The study demonstrates that reaction flash sintering can be a highly efficient technique for synthesizing bulk multicomponent ceramics for both material fundamental investigations and application development.