Quasielastic neutron scattering (QENS) has been used to study the relation between ionic mobility and conductivity at high temperature of the perovskite fluoride cryolite, Na3AlF6. Up to T=880 degrees C the conductivity is dominated by jump diffusion of Na ions. At higher temperatures, a considerable broadening of the QENS spectra and the development of a liquid-like diffraction peak is observed, The Q-dependence of the line width suggests a set-in of translational diffusion of fluorines at this temperature. This additional degree of translational movements could reason the jump-like increase in the ionic conductivity observed macroscopically. (C) 2008 Elsevier B.V. All rights reserved.