X-ray photoelectron spectroscopy (XPS) is a surface sensitive technique widely used for analysis of elemental compositions and oxidation states. The XPS facility at the University of South Carolina is a Kratos Axis Ultra DLD instrument equipped with a monochromated Al Ka x-ray source and hemispherical analyzer capable of an energy resolution of 0.5 eV. A sophisticated charge neutralization system enables XPS experiments to be carried out on insulating materials, such as oxide powders and polymers. The minimum detection spot size on the surface is 15 mm in diameter, and therefore surface chemical compositions can be determined with high spatial resolution. A catalysis cell directly attached to the XPS chamber allows the sample to be treated at high pressures up to several atmospheres with gases such as O2 and H2 and high temperature (<1000 °C); samples can be transferred from the catalysis cell to the XPS chamber without exposure to air.