Various types of organized assemblies; including micelle, planar multi-bilayer, bent multi-bilayer, fingerprint-like multi-bilayer, and multilamellar vesicles, were found in the aqueous system prepared by only one simple surfactant-alkylammonium chloride with a hydrocarbon chain length of 10 or 12. Electron microscopic images of the assemblies are provided. The properties of the system were characterized by DSC, fluorescence, and absorption probing techniques. It was found that the structure and shape of molecular assemblies in this system can be adjusted by very simple physico-chemical measures, such as pH adjustment and alcohol or salt addition. The mechanisms of formation and transformation of various molecular assemblies were discussed based on the mixing effect of the cationic amphiphile and the nonionic amphiphile which is only a hydrolysis product of the former.