Ionically conducting lanthanum fluoride (LaF₃), displaying a nanoscopic lamellar structure, has been synthesized at the surface of an aqueous solution of LaCl₃ and HF. The structure and the chemical composition of the conductor have been analyzed by SEM, electron probe microanalysis, X-ray powder diffraction, FTIR, and ¹⁹F magic angle spinning nuclear magnetic resonance (NMR) spectroscopy. The fluorine dynamics have been studied by NMR diffusometry and relaxometry in a temperature range from room temperature up to 875 K. The fluorine self-diffusion coefficient of the nanostructured LaF₃ is about two orders of magnitude larger than that of bulk LaF₃. This novel material is highly promising for many typical applications of fluorine ionic systems.