Mexican Institute of Petroleum 1 article published in JoVE Chemistry Determining the Chemical Composition of Corrosion Inhibitor/Metal Interfaces with XPS: Minimizing Post Immersion Oxidation Monika S. Walczak1, Perla Morales-Gil1,2, Turia Belashehr1, Kiran Kousar1, Paulina Arellanes Lozada1,3, Robert Lindsay1 1Corrosion and Protection Centre, School of Materials, The University of Manchester, 2Laboratorio de Caracterización de Materiales Sintéticos y Naturales, Instituto Mexicano del Petróleo, 3Departamento de Metalurgia y Materiales, Instituto Politécnico Nacional A protocol to avoid the oxidation of metallic substrates during sample transfer from an inhibited acidic solution to an X-ray photoelectron spectrometer is presented.