A method for producing monodisperse nanoparticles of metal or metal alloys, comprising:
- forming a metal-surfactant complex through a reaction of materials consisting of a metal precursor and a surfactant in a solvent to form a solution;
- heating said metal-surfactant complex solution gradually and continually at a rate of 0.1° C./min. to 20° C./min. up to a temperature of reflux for the solvent to cause an abrupt thermal decomposition of said metal-surfactant complex and instantaneous nucleation of the monodisperse nanoparticles;
- and
- separating said synthesized monodisperse nanoparticles of metal or metal alloys by adding a poor solvent without a size-selective precipitation step.