NOVELTY - Producing nanoparticles involves dispersing a molecular cluster compound and an initial portion of nanoparticle precursor composition to produce the nanoparticles in dispersing medium at a first temperature; increasing the temperature of the dispersing medium containing cluster compound and precursor composition to a second temperature to initiate seeding and growth of nanoparticles on molecular clusters of the molecular cluster compound; and adding at least one further portions of nanoparticle precursor composition to the dispersing medium containing growing nanoparticles.    USE - In the preparation of nanoparticle (claimed) which is useful as biological labeling; in solar cells, catalysis, biological imaging and light-emitting diodes.    ADVANTAGE - The method produces nanoparticles of any desirable forms; allows ready production of a monodisperse population of the nanoparticles with high purity. The method is more easily scaled-up. The method allows the molecular clusters as templates to seed the growth of nanoparticles. The precursor composition is periodically added to the reaction solution to keep the concentration of free ions to inhibit Oswards ripening and defocusing of nanoparticle size. The nanoparticle precursor composition is free of cadmium acetate and tri-p-octylphosphine selenide.    DETAILED DESCRIPTION - Producing nanoparticles involves dispersing the molecular cluster compound and an initial portion of the nanoparticle precursor composition to produce the nanoparticles in dispersing medium at a first temperature; increasing the temperature of the dispersing medium containing the cluster compound and precursor composition to a second temperature to initiate seeding and growth of the nanoparticles on the molecular clusters of the molecular cluster compound; and adding at least one further portions of the nanoparticle precursor composition to the dispersing medium containing the growing nanoparticles, where the temperature of the dispersing medium containing the growing nanoparticles is increased before, during and/or after the addition of each further portion of the nanoparticle precursor composition. The precursor composition comprises a first precursor species containing a first ion is incorporated into the growing nanoparticles and a second precursor species containing a second ion is incorporated into the growing nanoparticles.