Capillary electrophoresis is one of the prominent analytical separation methods. Currently, many computer programs exist which are able to predict the result of an electrophoretic experiment. Firstly, there are programs based on numerical solving of corresponding continuity equations and equations of chemical equilibria. Secondly, there are programs based on approximative models of capillary electrophoresis. Programs belonging to the first group are applicable to a wide range of modes of capillary electrophoresis and provide a precise solution. Their disadvantage is though a considerable time demand. On the other hand, the approximative models give the results almost immediately and, in addition, provide some theoretical relationships which are useful for optimization of the separation process. This dissertation thesis is focused on improvement and extension of validity of existing approximative models of capillary electrophoresis. As a part of this thesis, a model capable of a full-blown description of capillary electrokinetic chromatography is introduced. This model is implemented into program PeakMaster 6. The attention is also paid to a nonlinear model of electromigration without diffusion. This model enables a very good description of electromigration dispersion including effects related to...