Technical Abstract: Plant shoot tips do not survive exposure to liquid nitrogen temperatures without cryoprotective treatments. Some cryoprotectant solutions, such as plant vitrification solution 2 (PVS2), dehydrate cells and decrease the likelihood of lethal ice formation, but the extent of dehydration and the effect on water freezing properties is not known. We have examined the effect of a PVS2 cryoprotection protocol on the water content and phase behavior of mint and garlic shoot tips using differential scanning calorimetry. The temperature and enthalpy of water melting transitions in unprotected and recovering shoot tips was comparable to dilute aqueous solutions. Exposure to PVS2 caused dramatic changes in the behavior of water in shoot tips: the enthalpy of melting transitions decreased to about 40 J.g H2O-1, the amount of water that did not freeze increased to about 0.7 g H2O.g dry mass-1, and a glass transition (Tg) at –115 degrees C was immediately apparent. Evaporative drying at room temperature was also slower in PVS2-treated shoot tips compared to shoot tips receiving no cryoprotection treatments. We quantified the extent that PVS2 components permeate into cells and replace some of the water. Within cells, these components limit ice crystallization that would otherwise occur in unprotected shoot tips. Protection by PVS2 components occurred at temperatures in which the solution had not yet formed a glass. Protection is likely a result of controlled dehydration or altered thermal properties of intracellular water. A comparison of thermodynamic measurements for different cryoprotection solutions in diverse shoot tip systems will identify the efficacy of cryopreservation protocols.