The effect of hydrocarbon chain length on chemical selectivity in micellar electrokinetic chromatography (MEKC) was investigated using polymeric sulfated surfactants: poly-(sodium 7-octenyl sulfate), poly(sodium 8-nonenyl sulfate), poly(sodium 9-decenyl sulfate), and poly(sodium 10-undecenyl sulfate). Linear solvation energy relationships (LSERs) and free energy of transfer studies were conducted to predict the selectivity differences between the four polymeric surfactants. The overall nature of the solute/ polymeric micelle interactions was found to be different despite the fact that all polymeric surfactants have the same head group. The polar character and acidic strength of the polymeric surfactant are found to decrease as the hydrocarbon chain length of the surfactant is increased. On the other hand, the polarizability of the polymeric sulfated surfactants increases (upon interacting with solute lone-pair electrons) with increasing hydrocarbon chain length. The LSER results show that the solute size and hydrogen bond accepting ability play the key roles in MEKC retention.