The phase transition process of molecular assembly comprising cetyltrimethylammonium chloride (C(16)CA), cetyl alcohol (C16OH), and water was analyzed on the basis of dynamic viscoelasticity, mainly by using Cole-Cole plots. The assembly prepared at 75 degrees C showed onionlike multilamellar vesicles (0.2-5 mu m in diameter) immediately after preparation but transformed on aging into a rosary network of vesicles and finally fused into lamellae via polyhedra. The dynamic modulus (G') of the assembly monotonically increased with frequency, while the loss modulus (G ") showed 2 peaks. The change in the angle parameters (alpha(L), alpha(S)) calculated from Cole-Cole plots indicate the long and short time relaxation mechanisms, corresponding to the network of coagulated vesicles and lamellae, respectively.