He emigrated to Iraq, where he became professor of neurology and psychiatry at the Royal Medical School in Baghdad was.

From 1943 to 1945, Hoff performed military service in the Middle East and visited Afghanistan and Iran on behalf of the US government.

After the war Hoff worked at the Goldwater Memorial Hospital and at Columbia University in New York.

In his scientific work, he focused on experimental encephalitis studies, postural reflexes, psychosomatic problems, the influence of hypnotic orders on gastric and intestinal function, the psycho-vegetative circuit, the influence of endocrine glands by psychological factors, and the function of the hypothalamus, the central nervous system, of the metabolism and the endocrine glands, brain pathological phenomena, the function of the frontal, thalamic and cerebellum, time lapse phenomena, nervous vascular regulation, sleep studies, adrenal disturbances in infectious diseases, epilepsy, multiple sclerosis, psychopathy, and alcoholism.

Hoff is the founder of the Viennese Psychiatric School, whose first concern was to establish the humanization of the clinics to ensure the dignity of the mentally ill. Hans Hoff, in: Judith Bauer Měřínský: The impact of the annexation of Austria by the German Reich on the medical faculty of the University of Vienna in 1938: biographies of dismissed professors and lecturers .