The effects of prolonged (42 days) addition of deuterium-depleted water into rat’s diet on the functional state of the central nervous system in normal conditions and under conditions of normobaric hypoxia with hypercapnia were studied. It was also established that the use of deuterium-depleted water both in normal conditions and after exposure to oxidative stress contributes to a significant reduction in the emotional anxiety of animals. Prolonged use of deuterium-depleted water before hypoxic exposure (amnestic effect) helps to maintain learning and memory at the control level, i.e. it has a pronounced protective antiamnestic effect. In normal conditions, deuterium-depleted water does not affect the learning ability of animals.