Calorimetric scans of a number of low-hydrated phospholipids provide quite complex heat capacity profiles during the thermotropic main phase transition. This short study proposes some explanations that are based on experimental data obtained from four different methods (DSC, P-31-NMR, H-2-NMR, X-ray diffraction). The preliminary results show for POPC in which way DSC data are related to the melting of the hydrocarbon chains. Furthermore, the quadrupolar splitting data obtained from the H-2-NMR spectra of hydration water reveal how the water reorientation might contribute to the main phase transition of phospholipids. (C) 2013 Elsevier B.V. All rights reserved.