We synthesized nanocolloidal particles by a spark discharge in aqueous and nonaqueous solutions under an open environment, and determined the fundamental characteristics of the synthesized nanocolloidal particles. The experimental set-up of the discharge system is shown in Fig. 4, and the photograph of one type of solution plasma is shown in Fig. 5. Two metal wire electrodes were placed in an acrylate vessel. A bipolar direct current (DC) pulsed power supply was used to generate the spark discharge in the solutions.