AQTIVATE organized its first 3-weeks training workshop on ”Exascale computing and scalable algorithms” in Stockholm between 27 November 2023 and 14 December 2023. The fellows had the opportunity to be trained on topics including theoretical and practical aspects in the design of scalable algorithms for exascale High-Performance Computing; their adoption for linear solvers, eigensolvers and fundamental simulation algorithms; introduction to computer architectures, performance engineering and GPU programming.