A method is provided of producing nanoparticles in the size range 1 nm to 1000 nm through the synthesis of one or more precursor fluids. The method includes providing a fluid medium comprising at least one precursor fluid and generating an electrical spark within said fluid medium to cause pyrolysis of said at least one precursor fluid in a relatively hot plasma zone to produce at least one radical species. Nanoparticles are formed by nucleation in the fluid medium in a cooler reaction zone about the plasma zone, where the radical species acts as a reactant or catalytic agent in the synthesis of material composing the nanoparticles. The spark is created by an electrical discharge having a frequency between 0.01 Hz and 1 kHz, and a total energy between 0.01 J and 10 J. The nanoparticles may comprise silicon, or compounds or alloys of silicon, and are typically useful in electronic and electrical applications.