By investigating the L3 edge of Pd the objectives of this study are: (1) to uncover the interaction of CH4 and H2O with Pd species under reaction conditions, and (2) reveal the structural particularities of Pd sites leading to the fast inhibition and long-term H2O-deactivation behaviour for Pd/Al2O3 methane oxidation catalyst. To the best of our knowledge, this will be the first in situ / operando study on Pd-based methane oxidation catalysts exploring the tender X-ray energy range.