A high temperature non-aqueous synthetic procedure for the preparation of substantially monodisperse IV-VI semiconductor nanoparticles is provided. The procedure includes introducing a first precursor selected from the group consisting of a molecular precursor of a Group IV element and a molecular precursor of a Group VI element into a reaction vessel that comprises at least an organic solvent to form a mixture. Next, the mixture is heated and thereafter a second precursor of a molecular precursor of a Group IV element or a molecular precursor of a Group VI element that is different from the first is added. The reaction mixture is then mixed to initiate nucleation of IV-VI nanocrystals and the temperature of the reaction mixture is controlled to provide nanoparticles having a diameter of about 20 nm or less.