Abstract : A new embedded stationary phase, with quaternary ammonium and octadecyl chain, has been investigated in capillary electrochromatography (CEC). I have developed a process to pack the capillaries with such a phase. The electroosmotic flow (EOF), peak efficiency and a new parameter: the real electrokinetic porosity have demonstrated the presence of perfusive EOF. The latter parameter appears to be also a good evaluator of stationary phase wettability. I have estimated chromatographic retention in CEC for peptides in acidic conditions and demonstrated the good ability of mixed mode stationary phase for peptide analysis and peptide mapping. A comparison HPLC/CEC has indicated a strong difference of chromatographic retention mode between these two analytical modes and the original chromatographic behaviour in CEC. In our conditions, electrophoretic mechanisms played a major role in CEC. Although no electrostatic exclusion could be evidenced, retention by reversed phase retention was quite low.