Water electrolysis has since long been considered as a sustainable and scalable technology to generate green hydrogen, which is a promising candidate to store and liberate energy from. In order to increase the overall energy efficiency of this process, it is important to understand and improve the sluggish oxygen evolution reaction (OER) by developing more efficient electrocatalysts. Crucial in this search is the role dopants play in this process, as they severely impact the activity and stability of the electrocatalyst which can result in a positive or negative outcome. The main goal of this proposal is to reveal the impact of dopants, electrode nanoscale structure and microscale morphology on the stability of Ni-based OER electrocatalysts. Understanding and controlling the mechanism and processes behind the activity improvement caused by dopants of a diverse set of Ni containing catalysts will be achieved by a combination of high-end electrochemistry and (in-situ) physicochemical characterization both in idealized environments as continuous conditions. This will result in a complete understanding of the dopant activation/degradation mechanism, which can then be exploited to fine-tune and improve the proposed synthesis approaches and develop state-of-the-art Ni-based OER electrocatalysts that combine a high activity with a high stability.