Organic modifiers were effective both to extend the migration time window and to improve the separation of very hydrophobic compounds in MEKC.An iteration method was used to determine the migration time of micelles.The quantitative relationship between the capacity factor k’ and the concentration of organic modifiers was derived,which was investigated experimentally.The linear solvation energy relationships (LSER) methodology was applied to MEKC,and good linear relationships between Ink’ and solvatochromic parameters of 15 solutes were obtained in the presence of organic modifier in different concentrations,which indicated a new access in MEKC to predict k’ from the structural parameters of solutes.The effect of column temperature T on k’ was also investigated.