Since the industrial revolution, anthropogenic CO2 and other greenhouse gases in the atmosphere have been risen up leading to global warming. As a solution, the carbon capture and storage (CCS) technique has obtained a significant place due to its high efficiency. Sequestrating CO2 in deep saline aquifers is one of the most popular CCS techniques in the world due to its advantages such as extensive availability and huge storage capacity. The injected CO2 can be migrated upward in deep saline aquifers and it is prevented by a confining stratum that overlays the reservoir rock, made up of low permeable rocks such as claystone, mudstone, siltstone, or shale. Therefore, the permanence of CO2 storage completely depends on the integrity of the caprock seal over long periods of time. Thus, a thorough understanding regarding the hydro-chemico-mechanical behaviour of caprock with time is essential to secure the CO2 storage in deep saline aquifers; otherwise, injected CO2 may come out causing potentially deleterious changes in groundwater. Therefore, this research is aimed to obtain comprehensive knowledge on chemico-mineralogical and hydro-mechanical properties of the caprock in the long-term scenario under deep saline CO2 sequestration environment by conducting experimental studies and geochemical modelling to reduce CO2 leakage risks.