A method for making nanoparticles via metal salt reduction comprises, first, mixing metal salts in a solvent. Second, a reducing agent is added to the solvent at a temperature in the range of 100° C. to 350° C. Third, the nanoparticles dispersion is stabilized. Fourth, the nanoparticles are precipitated from the nanoparticle dispersion. Finally, the nanoparticles are re-dispersed into the solvent. The metal salt comprises a combination of FeCl2, FeCl3, Fe(OOCR)2, Fe(RCOCHCOR)3, CoCl2, Co(OOCR)2, Co(RCOCHCOR)2, and one of Pt(RCOCHCOR)2, PtCl2. The reducing agent comprises one of MBR3H, MH, M naphthalides, and polyalcohol; wherein R comprises one of H and an alkyl group, wherein M comprises one of Li, Na, and K. Long chain alkyl diols, and alkyl alcohol, can be used as a co-surfactant or a co-reducing agent to facilitate nanoparticle growth and separation.