Synchrotron X-ray scattering experiments make it possible to investigate dynamic structural changes in biological materials. This extremely high intense X-ray source is applied to the study of hydrated phospholipid multilamellar vesicles which undergo phase transitions. Time-resolved X-ray scattering experiments after temperature jump make clear the kinetics of the phase transitions. Real time X-ray scattering experiments at low temperature scan rates are the powerful methods for observing transient structural changes during the phase transitions.