Nanophase Ni 1 - x Zn x Fe 2 O 4 (x=0, 0.5, 1.0) samples were prepared by chemically precipitating hydroxides followed by hydrothermal processing. The products were characterized by X-ray diffraction and Mossbauer spectroscopy. Ferrite formation was found to be quite sensitive to the procedures adopted for preparing the hydroxide slurry prior to hydrothermal treatment. Nickel ferrite could be prepared in pure phase by co-precipitation as well as by mixing separately precipitated hydroxides. However, Ni 0 . 5 Zn 0 . 5 Fe 2 O 4 could only be prepared by co-precipitation. Leaving small amount of sodium in the slurry seems to obstruct pure phase formation of Ni 0 . 5 Zn 0 . 5 Fe 2 O 4 and results in partial formation of α-Fe 2 O 3 . A similar effect is observed in zinc ferrite.