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 has been analyzed by SEM, EPMA, XRPD, FTIR and 19F MAS 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 in the nanostructured LaF3 is about two orders of magnitude larger than in bulk LaF3. This novel material is highly promising for many typical applications of fluorine ionic systems.