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This paper reported a dry synthesis and characterization of cerium tetrafluoride (CeF 4 ) and cerium trifluoride (CeF 3 ) nanoscale polycrystals (NPs). The CeF 4 NPs were spherical or flaky and approximately 10 ± 2 nm in diameter. The CeF 3 NPs were rod-shaped nanorods with a length of about 150 ± 5 nm and a diameter of about 20 ± 2 nm. The first step was to synthesize the intermediate product—(NH 4 ) 4 CeF 8 by mixing CeO 2 and NH 4 HF 2 at a molar ratio of 1:6 at 390 K. The structural characterization was analyzed by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Then, (NH 4 ) 4 CeF 8 was heated in an argon gas flow to synthesize the CeF 3 and CeF 4 NPs. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The properties of CeF 3 and CeF 4 NPs were further evaluated by transmission electron microscopy (TEM), selected area electron diffraction pattern (SAED), and high-resolution transmission electron microscopy (HRTEM). The findings provided an alternative strategy for the synthesis of nanometer fluorides, which could be a reference for high-performance research on other nanometer fluorides.