A liquid phase plasma (LPP) process was used to synthesize of Ni-Cu bimetallic particles in aqueous solution. The bimetallic particles were well separated, and the particle size increased with increasing LPP process duration, causing these bimetallic particles to be well separated as the particle size increased when the LPP process time increased. The earliest stages of LPP formed dendrite-shaped nanoparticles, while spherical particles were generated in the later stages. While spherical Ni-Cu bimetallic nanoparticles were mostly observed in the initial stage, flower-like shaped Ni-Cu bimetallic nanoparticles were mostly observed after longer durations of plasma treatment. The solution pH decreased with increasing LPP process time.