Crystalline sodium tin paraperiodate has been prepared; the X-ray powder diffraction data are indexed to the hexagonal system.The thermal analyses, TG and DTA of MSnIO6, where M = NH4, Na, K, Rb, Cs, reveal that the initial mode of decomposition is via partial evolution of I2 and O2.The infrared spectra of these compounds exhibit six well-defined absorption bands. These bands are located within the frequency region characteristic of I—O vibrational modes suggesting a lowering of the normal Oh symmetry for the [IO6]5− species.The electrical conductivity υs. temperature behavior for CsSnIO6 is reported.