MultiXscale is a European High Performance Computing Joint Undertaking (EuroHPC JU) Center of Excellence in exascale-oriented application co-design and delivery for multiscale simulations. It is a collaborative 4-year project between members of the CECAM network and EESSI that will allow domain scientists to take advantage of the computational resources offered by EuroHPC JU. The MultiXscale Centre of Excellence will increase performance, productivity and portability (“the Three P's”) across the entire spectrum of scientists active in the domain of multiscale simulation. MultiXscale will pursue three pilot use cases of societal and industrial significance: · helicopter design and certification for civil transport, · battery applications to support the sustainable energy transition, · ultrasound for non-invasive diagnostics and biomedical applications.