A novel silicotungstate-based silver(I) compound, formulated as [{Ag8(H3mtz)12}{SiW12O40}2]·8H2O (1) (H3mtz = 3-Mercapto-1,2,4-triazole) has been hydrothermally synthesized. This compound was identified by the single-crystal X-ray diffraction, and also characterized by FT-IR, UV, TG, PXRD and elemental analyses. The data show that it possesses the octanuclear silver(I) clusters and the anionic silicotungstates, which were connected via the hydrogen bonds and weak Ag–O bonds. Interestingly, the estimated optical bandgap of compound 1 is 1.95 eV, which falls into the range of semiconductors.