The ionic conductivity (sigma(ac)) and the real part of complex dielectric permittivity (epsilon’) of F- conductor NH4Sn2F5 have been investigated between 300 and 380 K in the frequency range from 20 to 3.2 . 10(10) Hz. The crystals NH4Sn2F5 at the temperatures T-1 = 343 K and T-2= 357 K undergo two superionic phase transitions, accompanied by the anomalies of sigma(ac) and epsilon’. At room temperature and electric field frequency nu = 10(3) Hz, sigma(ac) = 5 . 10(-2) S/m and its activation energy Delta E(1) = 0.47 eV; at temperature T greater than or equal to 357, K sigma(ac)(T) changes with activation energy Delta E(2) = 0.34 eV. In the temperature range 343 less than or equal to T less than or equal to 357 K, sigma(ac)(T) dependence does not obey Arrhenius law. In this frequency region two relaxation dispersions of sigma(ac) and epsilon’ attributed to the ion transport in the grain and gain boundaries of our polycrystals have been found.