A gallium-based metal particle has been researched widely for heat management solution because of their unique properties primarily on the thermal conductivity. The mentioned particle could be used as a high thermal conductivity addition in microparticle-dispersed or nanofluid for advanced coolant or cooling medium. At the room temperature, however, Gallium-based metal has a liquid form due to its low melting point (c.a. 29.76°C). In this research, the liquid metal was immersed in a medium such as Ethanol and then sonicated for one hour to synthesize a solid Gallium-based metal particle. By this method, roughly 15% solid particle could be obtained from one gram of liquid metal. The size of the particle produced after synthesis was roughly at 200 - 350 μm, therefore, was still in micro-meter size. To reduce the dimension further, mechanical comminution method by ball milling was used. The ball mill process was done at 500 rpm for 10 hours. Polyvinyl Alcohol was used during ball mill process as a lubricant. The addition of a Gallium-based particle seemed to improve the thermal conductivity of the quench medium. The steel hardness increased roughly 20% after only 0.05% addition of Gallium-based particle in the quench medium.