Pure　Fe3O4　nanocrystals　with　different　sizes　were　synthesized　via　hydrothermal　processing　of　an　easily　obtained,　air-stable　metallorganic　molecular　precursor　(ferric　acetylacetonate:　Fe-(ACAC)(3))　in　20　vol.%　hydrazine　hydrate　aqueous　solution　at　80-160　degrees　C　for　0.5-12　h.　The　phase,　purity　and　size　of　the　resultant　products　were　characterized　by　powder　X-ray　diffraction　(XRD),　Raman　spectroscopy,　Fourier　transform　infrared　spectroscopy　(FTIR)　and　transmission　electronic　microscope　(TEM),　and　the　possible　formation　mechanism　of　Fe3O4　was　tentatively　proposed.　The　magnetic　properties　of　the　products　have　also　been　studied.　(C)　2009　Elsevier　B.V.　All　rights　reserved.