Cu-macrocyclic molecular catalysts exhibit very promising properties when anchored on inorganic semiconductor photocatalysts, e.g. WO3/BiVO4, by enhancing oxygen evolution reaction (OER) kinetics. However, a full understanding of the catalytic cycle underlying such enhancement is yet to be achieved. In order to address this issue, we request beamtime to perform operando photoelectrochemical (PEC) polarizarion dependent grazing incidence Cu K – edge XAFS measurements. A custom PEC cell was designed and 3D-printed in order to allow for X-ray fluorescence detection under bias and light stimulation. This will allow for real-time monitoring of catalyst oxidation state, coordination geometry and the orientation of the macrocycle with respect to the semiconductor in operational conditions. Due to the ultra-thin nature of the sample, the experiment will greatly benefit from the high brilliance of EBS, as well as from the grazing incidence and polarization-dependent setup.