The lithium ion mobility in three solid electrolytes (Li 8SnO 6, Li 7NbO 6, and Li 6In 2O 6) has been studied by NMR at several resonance frequencies from 170 to 500°K. The 7Li quadrupolar lineshape evolution shows the predominant influence on the conductivity mechanism of the vacancies in the octahedral sites of the oxygen close packing. In Li 8SnO 6, which has no vacancies, the lithium ions situated in the tetrahedral sites have the highest mobility. Spin-lattice relaxation times are in good agreement with the hypothesis of a Li 7NbO 6 2 D conductivity. The values of the activation energy, increasing from Li 7NbO 6 to Li 6In 2O 6 and to Li 8SnO 6, are found to be three times lower than those obtained from conductivity measurements.