This study concerns near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) studies of a Pt/A1203 diesel oxidation catalyst used in exhaust aftertreatment. We apply the technique to an industrial-grade porous catalyst, thus bridging both the pressure and materials gap, and probe the shift in binding energy of Pt 4d under different atmospheres. We observe that oxidizing atmospheres induce a shift in binding energy, corresponding to changes in Pt oxidation state, especially pronounced under an atmosphere of NO and O-2. Such changes in Pt oxidation state have previously been linked to dynamic changes in NO oxidation activity.