FT-IR and Raman spectra for polycrystalline powders of silver (I, III) oxide, AgO, and silver (I) oxide, Ag₂O, are reported. The vibrational spectra for each oxide are discussed in relation to its crystal structure, and were found to be consistent with factor group analysis predictions. Infrared and Raman spectroscopy, in conjunction with powder XRD, were also used to follow the thermal decomposition of AgO powder in air. Supplementary studies employing differential scanning calorimetry (DSC) and temperature programmed reaction (TPR), provided additional information relevant to the decomposition process. In agreement with mechanisms previously reported, AgO was thermally reduced to metallic silver ia two non-reversible steps, with the intermediate formation of Ag₂O. The transformation of AgO to Ag₂O occurred with heating in the 373–473 K region, while the product of this reaction remained stable to temperatures in excess of 623 K. Complete thermal decomposition of the Ag₂O intermediate to Ag and O₂ occurred at 673 K.