tThe characterization of the hydrophobicity of polymer compounds in solution remains a challengingissue of importance, especially for biomedical or pharmaceutical applications. To our knowledge, thereis no data of polymer hydrophobicity (log D) in the literature. In this work, for the first time, the logD distributions of cationic polymers were characterized using micellar or microemulsion electrokineticchromatography at physiological pH. The log D distributions of the polymer samples were obtainedfrom the electrophoretic/chromatographic retardation of the polymer derivatives in presence of neutralmicelles (or neutral microemulsion), using small cationic molecules for calibration. Separating elec-trolytes were based on a TRIS-chloride buffer containing a neutral surfactant (polyoxyethyleneglycoldodecyl ether) for the formation of micelles (in water) or microemulsion (in water/n-pentanol mixture).The log D distributions obtained at pH 7.4 using this method were in good agreement with the chemicalstructures of cationic polypeptides: poly(lys, phe) 1:1 > poly(lys, tyr) 1:1 > poly(lys, trp) 4:1 > poly(lys, ser)3:1 > poly(l-lysine), where x:y represents the molar ratio of each amino acid in the copolymer. Weightaverage octanol-water log D values and the dispersion of the log D distribution were also defined anddetermined for each polymer sample.