The main aim of this paper is to investigate the effects of gamma-irradiation on dielectric properties of barium salt of 12-tungstophosphoric acid (WPA) hydrate BaHPW12O40-7H(2)O (BaHWPA(.)7). Irradiation was carried out with two doses. Permittivity measurements have been performed in microwave X-band, at room temperature. After the irradiation (the absorbed dose 940 kGy) visible effect is the slight yellow color of the specimen and both real part epsilon' and imaginary p I art epsilon" of permittivity curves are shifted along the frequency axis. By measuring permittivity several days in succession gradual recovery of the specimen was observed. After five days epsilon' and epsilon" curves returned to their initial values on the frequency axis, and the color also disappeared. The second irradiation of the same specimen (1880 kGy) resulted in somewhat larger shift of epsilon' and epsilon" towards lower frequencies. This time, with larger absorbed dose there was no recovery effect and no-coloration. IR spectra of unirradiated and irradiated specimens were recorded and obtained data used for explanation of the observed phenomena.