We present the results of investigations related to the dielectric relaxation process in the composite material of BaTiO3 nanoparticles with the surface modified by hydroxyl groups and sodium oleate in polystyrene for the frequency range 1–140 kHz. The dispersion of the dielectric permittivity in the composite material with the volume fraction 5–35% is detected due to the presence of the relaxation process resulted in a blurred spectrum of relaxation times. It is found that the presence of surface’s modification leads to two effects related to the ac conductivity: a saturation of the frequency dependence and the further drastic growth, which may correspond to the specific hopping mechanism.