It is planned to investigate NiFe- and NiFeX (X = Cr, Mo, V, Nb) layered double hydroxides during electrochemical OER conditions. By application of in-situ X-Ray absorption (XAS) spectroscopy we hope to elucidate the electronic state and structure (XANES) of the catalyst materials. EXAFS will be used to compare interatomic distances (M-M, M-O) in the host structure (NiFe-LDH) with those in the NiFeX-LDHs, thus giving insight into the local structure of the catalyst and the influence of the guest species on the host.