In 2019, the European Union committed to achieving net-zero greenhouse gas emissions by 2050 through the European Green Deal, emphasizing the urgent need for mitigation technologies such as Carbon Capture and Storage (CCS). The efficiency of geological CO2 storage strongly depends on the fate of injected CO2, which is governed by the relative permeability functions of CO2–brine systems. These curves affect plume migration, residual trapping, injectivity, and surface facility design. However, reported measurements in the literature show significant variability, largely due to differences in laboratory protocols and the influence of capillary end effects (CEE). The thesis focused on finding the best method and practices for measuring the relative permeability for scCO2-brine systems.