Although gold does not form a native oxide under ordinary conditions, its surface can be oxidized electrochemically and the resulting oxide film studied. We have used this approach to examine the effects of anodization potential, anodization time, pH, and presence or absence of dissolved oxygen on the open-circuit decomposition of anodic gold oxide using a combination of in situ ellipsometric, potentiometric, coulometric, and microgravimetric measurements. As expected, increasing the anodization time or potential resulted in more inert films that persisted for longer times in the absence of an applied potential. We also found that this decomposition was faster at low and high pH, but slow at neutral pH. Decomposition of the oxide film was also inhibited by the presence of dissolved oxygen in the contacting electrolyte solution. (C) 2019 The Electrochemical Society.