We intend to determine the nature of ionic conductivity and the pathways of thermally induced diffusion in the inverse cubic perovskite BaLiF3. To this end, single-crystal neutron diffractometry at high temperature followed by careful analysis of the Debye-Waller factors including anharmonic contributions is necessary. Reconstruction of the scattering-length density using the maximum-entropy method (MEM) and derivation of probability-density functions (PDFs) allows mapping of the actual ion pathways. The associated effective one-particle potentials (OPPs) give access to the energy barriers for migration. Comparing these results to powder neutron diffraction, high-temperature NMR investigations (Prof. Wilken-ing, Graz), and quantum-chemical computations (Prof. Bredow, Bonn), we hope to acquire a fundamental understanding of mobility in potential two-ion conductors and lay a foundation for further experiments with mixed anion sets.