Temperature-controlled vesicle aggregation was investigated in a catanionic surfactant system of sodium n-dodecyl sulfate/n-dodecyltributylammonium bromide. Vesicle aggregation took place as the temperature reached the critical value (T-c). T-c can be adjusted by the variations of the total surfactant concentration and the mixed molar ratio. It was also found that the temperature variation above T-c can greatly influence the vesicle aggregation rate. The vesicle aggregation process was irreversible as long as T >= T-c whereas the vesicle disaggregation process occurred only below T-c.