Heterogeneous catalysis of nanoparticles has recently emerged as highly promising way to speed up catalytic processes due to their far higher surface area compared to bulk materials. But they face significant challenges in achieving high catalytic activity and sufficient durability. A key problem has been that all existing approaches to the characterization of atomic scale phenomena in these materials either lack structural specificity or can be employed under highly unrealistic catalytic environments. As an example, operando x-ray catalysis has often been carried out under idealized conditions and averaging information from macroscopic facets. This approach suffers from the lack of transferability to nanocrystalline systems. To tackle this problem, I am developing new state-of-the-art in situ techniques based on coherent x-ray scattering and complementary chemical characterization, with which I will optimize catalyst and reactor operations simultaneously. This is the ambition of the CHARLINE project to study in situ and operando the structural evolution of catalytic nanoparticles in realistic conditions during reaction by using the unique capabilities of coherent diffraction Bragg imaging (CDI). My proposed work builds on my recent exciting proof-of-concept experiments using Pt nanocrystals that demonstrate the sensitivity and spatial resolution of CDI under liquid conditions. As dedicated instruments for CDI have just reached user operation, it is only now that this new imaging technique can be applied during reaction and can probe structural changes of individual nanocrystals under conditions where up to now, no other techniques could probe the relevant parameters. My project will shed light into most relevant unsolved issues (durability, activity…) that limit the efficiency of today’s industrial processes and will open new horizons with outstanding impact in catalytic research.