The metal ion effect on hydrated phospholipid bilayers of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG), suspended in an aqueous solution placed in a zinc selenide cylindrical internal reflection cell, is studied by means of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The infrared spectra revealed that DPPG liposomes are more unstable than DPPC liposomes with changes in temperature and in the presence of metal ions. In the presence of Ca2+, both DPPC and DPPG liposomes show a conformational change and dehydration as is evident by the ester carbonyl stretching mode. The dehydration ability of metal ions decreases in the order of Ca2+ much greater than Mg2+ > Ba2+ in the phosphate ester group of DPPG. The effect of increasing Ca2+ and Mg2+ concentration is cumulative; however, Ba2+ does not demonstrate a concentration dependence. The infrared spectra and DSC thermograms indicate that dehydration is the main cause of the transition temperature shift.