Ion mobility and transport properties of the fluorite-type solid solutions 50PbF(2)-30BiF(3)-20RbF, 50PbF(2)-30BiF(3)-20CsF and 50PbF(2)-25BiF(3)-25CsF were studied by F-19 NMR spectroscopy and conductivity measurements. An analysis of F-19 NMR spectra made it possible to assess the temperature effect on the nature of ion motions in the fluoride sublattice, to identify types of ionic mobility, and to determine the corresponding temperature ranges. The results showed that in these solid solutions at temperatures above 400 K the dominant type of ion motion is a diffusion of fluoride ions. The F-19 NMR data correspond qualitatively to the results of conductivity measurements. A dependence of the ion mobility and conductivity on the nature of the alkali cation was studied in the 50PbF(2)-30BiF(3)-20MF solid solutions (M = Rb, Cs). The sample with 20RbF has the highest ionic conductivity of 2.6 x 10(-2) S/CM at 500 K. (C) 2014 Elsevier B.V. All rights reserved.