Geosynthetic clay liners (GCLs) are commonly used as hydraulic barriers in many waste containment facilities. Bentonites in GCLs typically have a high swelling capacity and a low hydraulic conductivity. But, the severe exposure conditions encountered by GCL in field conditions can deteriorate its hydraulic performance due to cation exchange reactions. To overcome this problem, researchers used polymers to modify the bentonite in GCL. The current study evaluates the use of super absorbent polymer (SAP) for modifying bentonite by adopting the in-situ polymerization technique. In the initial part of the study, the SAP was synthesized by using the design of experiments technique to optimize the chemical composition. An empirical model was developed using the MINITAB software, and the effect of various design factors was investigated. After polymer optimization, the polymerized bentonite (PB) was developed, characterized, and examined for chemical compatibility. The impact of various pore fluids on the index properties of PB was examined. For chemical compatibility assessment, a constant flow apparatus was newly fabricated. The results of index properties and permeability of PB will be discussed in this seminar.