Microemulsion electrokinetic chromatography (MEEKC) was investigated with the goal of elucidating the influence exerted by the amount of lipophilic organic phase and the amount of co-surfactant on the migration of a number of neutral test solutes. Furthermore, MEEKC was compared to solvent-modified micellar electrokinetic chromatography (MEKC). The organic solvents methanol, ethanol, 1-propanol, 1-butanol, acetonitrile, tetrahydrofuran, and 2-ethoxyethanol serving as co-surfactants in MEEKC were used in similar concentrations in MEKC systems in order to compare the selectivity and separation efficiency of the two kinds of system. The solvent-modified MEKC technique proved to be very similar to MEEKC in performance with respect to both separation selectivity and efficiency of separation.