The study aimed to determine the psychological aspects of captivity in the War in the East of Ukraine: the purposes and motives of the capture of Ukrainian Forces (UF); the types of captivity and their specifics; the stages and phases of captivity. The measures included a questionnaire and interview method. 694 former prisoners of war (POWs) (servicemen of the Armed Forces of Ukraine and soldiers of volunteer battalions) participated in the study. The research results revealed the purposes of capturing UF: to stop UF advance; obtaining intelligence; demoralization of UF; demonstration of military superiority; capturing prisoners for exchange; unwillingness to kill; receiving a ransom. The UF invaders were military units, professional mercenaries’ units, and gang formation units. The stages of captivity (capture and transportation to a place of permanent detention; first interrogation; being held captive; exchange of POWs and homecoming) were characterized by intimidation, aggression, physical, psychological and sexual violence against POWs, the purposeful creation of an environment of mass psychosis among POWs. Captivity kept the POWs in constant tension and fear. The altered mental status of POWs took place in successive phases: life reactions, shock, psychological demobilization, denouement, recovery, and conflict phase.