Dielectric investigations in the temperature and frequency ranges 150 - 450K and 102 - 105Hz respectively show that the compositions x = 0.2 and x = 0.4 of the solid solution Rb1-x(NH4)xHSO4 are ferroelectric below Tc = 285K and Tc = 295K respectively. The symmetry of room temperature phase is P21/C for both investigated compositions. Alternative current complex impedance measurements were performed on this ferroelectric
and superconductor material at high temperatures. An impedance relaxation was observed. In addition, to the ferroelectric properties, a modest level of conductivity at high temperatures, which was attributed to the motion of H+
proton, was observed for both compositions but this conductivity is more pronounced at low and high temperatures for the composition x = 0.2.
