By 1912, the strains of politics were beginning to take a toll on Kočić's mental health, and he vacated his position on the Administrative and Cultural Council the following year. He spent the subsequent months at a resort near Mount Ivan, in central Bosnia, but the state of his mental health remained poor. In January 1914, Kočić was admitted to a Belgrade mental hospital, where he died on 27 August 1916, amid the chaos of World War I and the city's occupation by Austria-Hungary. By some accounts, Kočić committed suicide, but this has been denied by his family. He was survived by his wife Milka and daughter Dušanka, who went on to become a professor. The couple also had a son, Slobodan, who predeceased his father. Kočić's remains were buried at Belgrade's New Cemetery.