Displacement current across multilayer films of lipid membranes was measured with thermal stimulation and the critical temperature of membrane films due to phase transition from ordered gel to disordered fluid was determined. The membranes used here were L-α-Dilauroyl, Phosphatidylcholine (DLPC) and L-α-Dimyristoyl, Phosphatidylcholine (DMPC). The phase transition temperatures of DLPC and DMPC were determined 43°C and 78°C, respectively.