Bentonite and Organoclay were mixed with natural soil in varying proportions for their assessment of suitability as material for landfill liner. The admixtures had the organoclay ranging from 10 to 20%, and bentonite in the range of 0 to 10%. The admixtures were subjected to laboratory investigations for determination of (i) sorption characteristics of admixtures with respect to TOC; (ii) hydraulic conductivity using flexible wall permeameter; and (ii) effective molecular diffusion coefficient for Chloride and TOC through these three admixtures. The results of laboratory investigations show that although bentonite is desirable for low hydraulic conductivity of landfill liners, the effective molecular diffusion coefficient decreases considerable with higher amount of organoclay. Retardation coefficient of the admixtures was determined by curve fitting the experimental data of sorption tests to fit to Freundlich (nonlinear) sorption isotherm. Admixtures with higher content of oraganoclay were found to be having higher retardation factors. One dimensional transport simulations were performed, to evaluate completely, the effectiveness of these materials for use as landfill liner and to develop design charts for determining required liner thickness