Bi/Ag-I thin films have been deposited on glass substrates using co-precipitation method. Investigation of the Bi-Ag-I thin film was made of structural and optical properties. The structures of the films were characterized by X-ray diffraction and scanning electron microscopy. Uniform distribution of grains was clearly seen in the photograph of scanning electron microscope under the 90° deposition temperature. The optical properties were investigated with UV-visible. The transmittance and optical band gap (E g) were increased with pH which was up to 80 % and 4.02 at 70° deposition temperature. The structure of BiI3 was observed in XRD analysis at 90° deposition temperature. The atom planes were changed with deposition temperature. The film thickness of Bi/Ag-I thin films changed irregularly with deposition temperature.