READEX is a EU Horizon 2020 FET-HPC project whose objective is to exploit the dynamism found in high-performance computing applications at runtime to achieve ecient computation on Exascale systems. In this paper, we describe the use of the READEX methodology to investigate dynamic behaviour of PRACE-relevant applications at runtime and describe how such application dynamism can be exploited to tune a range of application-, system software- and hardware-level parameters for improved performance and energy eciency on current and future European extreme-scale systems.