We have studied the chemical bonding in thin films of SiOx (x<2) by Auger electron spectroscopy (AES). We have compared the AES Si LVV spectra of suboxides of silicon with the AES Si LVV spectrum of stoichiometric SiO2 and have observed that the spectra of the suboxides are characterized by the emergence of a feature associated with Si–Si bonds that are present in the suboxides but not in stoichiometric SiO2. We have taken care to distinguish between spectral features that are associated with departures from SiO2 bulk stoichiometry, and features that are generated by ion and electron beam induced surface damage. Ion and electron beam induced damage produces changes in the surface composition that also generates AES spectral features associated with Si–Si bonds. We have based our interpretation of the additional AES spectral feature in the silicon suboxides on an empirical tight-binding model calculation for the electronic structure. This calculation shows that Si–Si bonding states in the suboxides appear near the middle of the energy gap of stoichiometric SiO2. The position of the new spectral feature in the suboxides is in agreement with the predictions of the model calculation.