In capillary electrophoresis, the relative orders of mobilities of analyte, additive, and the complex formed determine the analyte peak shape in a way similar to the way the binding isotherms determine the peak shapes in chromatography. The three mobilities allow six possible orders; each produces a characteristic peak shape in CE. Equations describing the analyte migration in a CE system with the presence of mobility-changing additives can be implemented into computer programs to predict the migration times of the analyte peak maximums, and the predicted migration times agree well with the experimental results.