During the last 6 years, chemical relaxation studies of the kinetics of micelle formation in triblock copolymers such as L64 (EO13PO30EO13) and B40 (EO13BO10EO13) which behave as nonionic surfactants have been studied. The micellar system is characterized by two well-defined relaxation times as predicted by Aniansson and Wall for the isodesmic model A1 + An-1 ⇌ An in which monomeric A1 and micellar, An, are the principal species. A closer examination of the published work, however, reveals that some issues have not been satisfactorily resolved. For example it is claimed that the fast relaxation time associated with the single step monomer/micelle exchange exists in two time domains, namely, 10-4−10-5 s (T-jump) and 10-7 s (ultrasonic) for the same triblock copolymers. In an attempt to resolve this predicament, we report here some ultrasonic relaxation measurements on a number of triblock copolymers as micellar systems and also as mixed micellar systems in the presence of hexadecyltrimethylammonium bromide...