The present investigation reports on a simple technique for the preparation of single-phase BiFeO3 powders using the polymerized complex method, starting from iron and bismuth nitrates. A mixed aqueous solution with citric acid, ethylene glycol, Bi, and Fe ions was polymerized. The formation mechanism, the homogeneity, and the structure of the obtained powders have been investigated by thermogravimetry, X-ray diffraction (XRD), Raman spectroscopy, and scanning and transmission electron microscopy measurements. XRD results demonstrated that thermally induced crystallization of rhombohedral BiFeO3 from the Bi-Fe polymeric precursor occurred at temperatures as low as 400 degrees C. Pure single-phase BiFeO3 nanocrystallites without any impurity or amorphous phases were obtained when the precursor was treated at 600 degrees C for 3 h.