The F- ion transport and diffusion properties inside the solid solution Pb1-xCrxF2+x (0 less than or equal to x less than or equal to 0.12) with fluorite-type structure have been determined by impedance spectroscopy and F-19 NMR investigation. The various electrical parameters of Pb1-xCrxF2+x are compared with those of Pb1-xAlxF2+x (0 less than or equal to x less than or equal to 0.12) whose structure derives also from the fluorite-type. The Cr3+ substitutional cation is of a slightly larger size than the Al3+ cation but both cations offer the same usual coordination (CN = 6) in ternary fluorides. Comparison of F-19 NMR specrra of some compositions Pb1-xMx'F2+x (M' = Al, Cr) at different temperatures has been realized in order to discover whether the clustering process proposed in Pb1-xAlxF2+x can be extended to Pb1-xCrxF2+x.