Results of a study on sorption and diffusion of chlorosulfonated polyethylene geomembrane with methyl benzoate, ethyl benzoate, methyl salicylate, iso-butyl salicylate, phenyl acetate, and diethyl phthalate in the temperature range 25-60 degrees C are presented. A gravimetric sorption method is used to calculate the diffusion and permeation coefficients from the Fickian relationship. The diffusion results are dependent on penetrant-membrane interactions, temperature, and on penetrant concentration. The values of diffusion coefficients range from 0.02 x 10(-7) cm(2) s(-1) for diethyl phthalate at 25 degrees C to 1.81 x 10(-7) cm(2) s(-1) for ethyl benzoate at 60 degrees C. The activation energies for diffusion range from 21 to 50 kJ mol(-1). The values of heat of sorption ranged between 2.2 and 6.4 kJ mol(-1). Sorption results are also analyzed using a first-order sorption kinetic equation. Experimental results and calculated parameters are used to discuss the transport behavior. None of the esters used have shown any chemical attack toward the geomembrane.