Bismuth ferrite nano-and microcrystals were prepared by a facile molten salt technique in two kinds of molten-salt-based systems (NaCl-KCl and NaCl-Na2SO4). In the NaCl-KCl salt system, a systematic study indicating the effects of process parameters (e.g., calcination temperature, holding time as well as the molten salt ratios) on the bismuth ferrite formation mechanism and structural characteristics is reported. The results show that almost pure phase BiFeO3 powders with minimum impurity phase of Bi2Fe4O9 were synthesized at temperatures of 700 degrees C-800 degrees C, whereas high calcination temperature (e.g., 900 degrees C) resulted in the formation of almost pure phase Bi2Fe4O9 powders. The prolonged holding time increased the particle size via the Ostwald ripening mechanism; however, there was little effect on the particle morphology. Similar phenomenon occurred as increasing the molten salt ratios. In the NaCl-Na2SO4 salt systems, it is found that low NP-9 (nonylphenyl ether, NP-9) surfactant content (0-5 mL) led to the formation of almost pure phase BiFeO3 powders, whereas high NP-9 surfactant content (e.g., 20 mL) resulted in pure phase Bi2Fe4O9 powders. The average particle size of the BiFeO3 powders was decreased as increasing the NP-9 surfactant content, whereas their morphologies did not change significantly. Because of the simplicity and versatility of the approach used, it is expected that this methodology can be generalized to the large-scale preparation of other important transitional metal oxides with controllable sizes and shapes.