The study is a continuation of our investigations on understanding mechanistic details of three-way catalysts (TWC) by exploring for the first time the L edges of the noble metal components (proposal MA-4916 on Pd L edges) under in situ / operando conditions. With this proposal we aim at completing our operando HERFD-XANES study on Pd L edges for a Pd/CeO2-ZrO2 three-way catalyst under applied reaction conditions. In a similar manner, we would like to investigate Rh L edges for a Rh/CeO2-ZrO2 TWC. The obtained results will help to: (1) uncover the interaction of CO, C3H6 and NO with the noble metals under reaction conditions, and (2) perform spatially resolved measurements along the catalyst bed at selected temperatures during LOff/LOut for elucidating essential mechanistic aspects.