The operational parameters and factors which control the performance Ž . of capillary electrochromatography CEC using commercially available CEC instrumentation are evaluated and discussed. The CEC of neutral or ion-suppressed acidic analytes shows marked advantages such as increased column efficiency and reduced analysis times compared to conventional high-performance liquid chro-Ž . matography HPLC . Development of the CEC method using C-18 stationary phases follows similar guidelines to that of HPLC and, due to the high efficiencies obtained, the time required for method development can be substantially reduced. The technique of CEC is extremely attractive for the analysis of pharmaceuticals due to its excellent quantitative characteristics: good repeatability, reproducibility, wide UV detector linearity, and excellent detection limits. The analysis of acidic and neutral analytes by CEC using reverse-phase material is highly successful. However, in order to analyze highly basic analytes a strong cation exchange stationary phase is needed. This phase can produce staggering and as yet unexplained ''apparent'' efficiencies of over 40 = 10 6 plates per meter; however, to-date these results are highly non-reproducible. The application of CEC to the pharmaceutical industry has been demonstrated in the analysis of a wide range of structurally diverse pharmaceutical compounds using capillaries packed with reverse-phase materials.