This paper determines that permeating organic fluids through compacted kaolinite does not significantly change the distribution of different pore sizes. The mercury intrusion method was used to quantify the pore size and frequency distribution of specimens before and after permeation with nitrobenzene, acetone, phenol, and benzene. Porosity quantification parameters obtained from available hydraulic conductivity models were then correlated with experimental values of absolute permeability. Acetone and phenol resulted in changes of absolute hydraulic conductivity within one order of magnitude, that of 0.01 N calcium sulfate (CaSO4) solution, while benzene and nitrobenzene led to a decrease of two orders of magnitude. Mercury intrusion tests on all specimens indicated that the size and distribution of pores within the 0.008 to 10 μm range were not significantly changed. The conclusion is that changes in hydraulic conductivity of compacted kaolinite are not due to a redistribution of pore sizes due to changes in forces of interaction. The results suggest that the decrease in hydraulic conductivity with benzene and nitrobenzene are due to the low solubility of these chemicals in water.