The structures of α-and β-Ag 3 VO 4 were studied via single-crystal X-ray diffraction (XRD). The transition from α-phase to β-phase was found to occur at 110 °C. Single-crystal XRD revealed that the integrity of the single crystals was maintained as Ag 3 VO 4 reversibly transitioned between α-Ag 3 VO 4 and β-Ag 3 VO 4 . The optical and electrical properties of polycrystalline α-Ag 3 VO 4 were studied by diffuse reflectance spectroscopy and impedance spectroscopy. In order to assess the optical and electrical properties of β-Ag 3 VO 4 , in situ measurements were performed above the phase-transition temperature. Thin films of α-Ag 3 VO 4 were prepared by combinatorial sputtering and pulsed laser deposition (PLD). The crystallo-graphic, optical, and electrical conductivity properties of the α-Ag 3 VO 4 thin films were compared with the bulk properties. KEYWORDS: α-Ag 3 VO 4 , β-Ag 3 VO 4 , single crystal, thin film, electrical conductivity