Changes in electronic structure and bonding at metal-oxide interfaces can have a pronounced influence on the macroscopic properties of the interface. This is particularly true for supported-metal catalysts, which feature nanometer-sized transition metal particles dispersed on an inert support such as A12O3 or SiO2. Variations in the d-band filling of the transition metal due to chemical bonding with the support could potentially alter the chemical activity of metal atoms near the interface, thereby affecting catalyst performance. This work investigates possible interface contributions to the performance of a model Ni- SiO2 catalyst system by directly assessing the nature of bonding at the metal-oxide interface. Electron energy-loss spectrometry (EELS) in the TEM is used to examine and quantify changes in the d-band occupancy of interfacial Ni atoms relative to the bulk, and to further relate these changes to interface chemistry.The Ni d-band occupancy is evaluated using the integrated area under the Ni L2,3 edge in the energyloss spectrum, according to routines establishe-i previously.