Shale reservoirs and their capacity to store absorbed greenhouse gases, mainly CO 2 , have come to the forefront of scientific discourse as a result of the global effort to alleviate concerns about the increase in global temperature. Many nations and companies have started several programs to analyze the security and viability of storage to do this. There is a dearth of information about shale's electrokinetic properties despite the vast amount of literature on shale exploration, its composition, and enhanced gas recovery from shale. This characteristic determines how the shale sample reacts to various fluids, its wetting state, and how it preferentially reacts with some gases (CO 2 over CH 4 ). Eagle Ford shale sample's electrokinetic properties (surface charge and colloidal stability) are presented in connection to its capacity as a CO 2 storage system for the first time. Zeta potential measurements were used to determine this, and the impact of salinity in freshwater and marine environments was examined. Results indicate that the Eagle Ford shale sample is colloidally unstable and negatively charged in both marine and freshwater environments. Furthermore, the sample is a strong candidate for the release of cations for CO 2 mineralization due to its colloidal stability. The sample's mineralogy, total organic content, and the environment pH, on the other hand, determine its surface charge and colloidal stability. Furthermore, the results demonstrate that the Eagle Ford shale sample's colloidal stability is enhanced by continuous injection of CO 2 -rich fluid. As a result, injection reduces the tendency of cations to liberate for CO 2 mineralization. However, the electrokinetic properties are unaffected by the injection time scale. Eagle Ford shale's electrokinetic properties presented in this study can be used to understand not only the potential and security of CO 2 storage but also the various behaviors of shales and other minerals during CO 2 mineralization.