The aim of this investigation was to develop a method using capillary electrophoresis to determine the critical micelle concentration (cmc) and to gain insight on the formation of the micelles of the transquilizer chlorpromazine hydrochloride (CPZ). CPZ was commonly used as an antipsychotic drug to treat schizophrenia. The CPZ samples were dissolved in a 0.1 M phosphate buffer solution at a pH of 6.5. Two methods were employed depending on the resolution of th data obtained; one examined the change in the retention time and the other focused on the relative area. Both approaches found the cmc to be in close proximity to the known cmc value of 3.2 mM at pH 6.5. Furthermore, our results suggest that the micelles were formed following a stepwise aggregation process.