In this work, we systematically investigated the formation of Au oxide on Au POSCs by HV electrolysis and the subsequent formation of a NPG film formed by electrochemical reduction of the Au oxide. The HV electrolysis was performed in the normal electrolysis region (at 300 V) and in the aCGDE region (at 540 V) for different times (100 ms to 30 s.) From electrochemical measurements, we infer that for both conditions the thickness of the Au oxide film increases with increasing electrolysis time, with a stronger increase for electrodes prepared at 300 V. Overall, the Au oxide films are mostly homogeneous on the POSCs for all conditions, except for HV electrolysis at 300 V for 30 s. In that case, the Au oxide shows different structures depending on the crystallographic orientation of the substrate and adhesion seems to be weakest on the low-index facets, i.e., Au(111) and Au(100). Grain boundaries were found to play no role in the quality of the Au oxide or NPG films. In regions where the Au oxide film is inhomogeneous or exfoliated, also inhomogeneous or exfoliated NPG films are obtained. The NPG film formed from Au oxides prepared by HV electrolysis at 300 V is mostly homogenous on all facets up to 15 s electrolysis time. In turn, NPG films obtained from thin Au oxides prepared by HV electrolysis at 540 V tend to exfoliate even though the Au oxide film is homogeneous. This process seems to be facet-dependent and films are less stable on Au(111) or Au(111*) facets than on Au(100) or Au(100*) regions. The stability increases with increasing Au oxide thickness (longer electrolysis times). From our experiments, we cannot deduce whether the NPG film exfoliates during the electrochemical reduction of the Au oxide or during the emersion of the electrode from the electrolyte. Gaining more fundamental insights into the exfoliation process could be beneficial to either find ways to systematically exfoliate NPG from a bare Au substrate or to form stable NPG films on a bare Au substrate.