NiFe2O4 nanoparticles and nanorods were synthesized by a facile hydrothermal treatment of Ni(DS)(2) (Nickel dodecyl sulfate), FeCl3, and NaOH aqueous solution at 120 A degrees C. The products were characterized by powder X-ray diffraction, transmission electron microscopy, and selected area electron diffraction. The magnetic properties were evaluated using a vibrating sample magnetometer. The probable mechanism of the formation of NiFe2O4 nanoparticles and nanorods was discussed.