Crystallisation processes affect the rheological properties of magma like its viscosity and buoyancy. It has a direct impact on its ability to migrate in the crust and erupt. Here we propose for the first time in situ crystallisation experiments to study crystal nucleation and growth in a basaltic magma at high pressure and high temperature under water saturated conditions. We will combine fast synchrotron X-ray microtomography with a unique Internally Heated Pressure Vessel to simulate magma storage conditions within the crust at pressures <150 MPa and temperatures <1200 °C in presence of volatiles (H2O). These experiments will allow us to capture, visualise and quantify crystallisation kinetics in basaltic magmas at pre- and syn-eruptive conditions, fundamental to improve models and our understanding of magma dynamics with major implications for the volcanic risk mitigation associated with basaltic systems.