Click chemistry by copper-mediated azide/alkyne cycloaddition reaction is known as a very efficient synthetic pathway for chemical coupling and for surface functionalization. The attractiveness of this reaction is due to the selectivity of the reaction of azides and alkynes. Nevertheless, the control of the kinetics of the reaction and the characterization of the reaction products requires the use of adequate analytical techniques. This is especially the case for the monitoring of the functionalization of polymeric compounds and the control of the homogeneity of the chemical composition of these products. In this work, the third generation of dendrigraft poly-l-lysines derivatized with acetylenic groups was decorated with tryptophan-PEG-azide arms via triazole ring formation. Pressure assisted capillary electrophoresis was used to monitor the progress and the kinetics of the click chemistry reaction. As expected the click product was obtained with excellent yields within 20 min reaction time at room temperature. Diffusion coefficients and hydrodynamic radii of dendrigraft poly-l-lysines and their click reaction products were determined by Taylor dispersion analysis. Finally, capillary electrophoresis was found very useful to check the purity and the homogeneity in the chemical composition of the decorated structures.