Tl3(PW12O40) semiconducting thin films have been synthesized by using simple chemical bath deposition technique. Morphological, optostructural and thermal properties of the title compound have been characterized by SEM, EDS, XRD, UV-VIS, electrical resistivity, thermoelectric power, TGA-DTA techniques. SEM and XRD data of material shows that, it is polycrystalline and having simple cubic spinel structure. UV-vis spectroscopy revealed that, Tl3 (PW12O40) heteropolyoxometalate material is a direct gap semiconducting material with band gap 2.7 eV. The dc electrical resistivity and thermoelectric power was measured in the temperature range 300-573ºK .The variation of resistivity with respect to temperature showed there is negative resistance region indicating semiconducting nature of material. The thermoelectric power for sample was positive over the whole range of the temperature showing that it is p-type semiconductor. EDS of sample shows that, the Tl (I) is intercalated in phosphotungustate anion. The TGA-DTA study revealed that, material is thermally stable up to 265.12oC.