Sporadic catalytic decomposition because of the presence of Au grains is a significant issue to be clarified in electronic devices. Here, we report the inhomogeneous dissociation of native silicon oxide depending on the electronic structure of Au grains using scanning photoelectron microscopy. Upon annealing, the oxygen atoms dissociated from native SiO x layer out-diffuses in nonuniform manner, resulting in oxidize the Au layer. Valence band spectra showed that the spit-orbit splitting, directly related to the coordination number, differs from site to site. Scanning photoelectron microscopy images show that dissociated SiO x coincides with the regions where low-coordinated Au resides. These results imply that Au with low coordination number activated the dissociation of SiO x and open new pathway to remove undesirable oxide layer at relatively low temperature. 2 ), contrasted by the intensities of the Si 2p 3/2 level from neutral Si (E B = 99.7 eV), of the sample (d) before and (e) after annealing at 500°C for 1 h. (f) SPEM image of the annealed sample, contrasted by intensity ratios of the oxidized Si 2p 3/2 (E B = 103.5 eV) to the Si 2p 3/2 (E B = 99.7 eV) from neutral silicon atoms. [Colour figure can be viewed at wileyonlinelibrary.com]