In this work, nine homologous ion-pair amphiphiles (IPAs) were successfully prepared by the precipitation or ion-exchange methods. This demonstrated the feasibility of designing and synthesizing lipid-like amphiphiles from cheap and abundant single-chained cationic and anionic amphiphiles. The thermotropic transition behavior from gel phase (L beta) through rippled phase (P-beta') to liquid-crystalline phase (L-alpha) of these IPA bilayers in water was thereafter systematically studied by using differential scanning calorimetry. A database of pretransition temperature, main transition temperature, and the corresponding transition enthalpy/entropy of the nine IPA bilayers was documented. Different phase transition behavior is exhibited by IPA bilayers with different hydrocarbon chain lengths and symmetry. The main phase transition temperature (T-m) is consistently higher for IPAs with higher total number of carbon atoms in the hydrocarbon chains. For IPAs with the same total number of carbon atoms in the hydrocarbon chains, the T-m is higher for the symmetric one than that of the asymmetric one. Furthermore, much higher T-m was exhibited by IPA as compared with that of phosphatidylcholine based on the same total number of carbon atoms in the hydrocarbon chains. These fundamental properties of IPAs definitely help understand membrane characteristics of catanionic vesicles, which were fabricated from IPAs, for potential applications in drug delivery and gene therapy.