Reynaldo Bignone has been convicted over torture and kidnappings committed during the nation's 1976-1983 military regime and sentenced to 25 years in prison.
Bignone, 82, was convicted along with five other former military officers for 56 cases involving torture, illegal detentions and other crimes in one of Argentina's largest torture centres, the Campo de Mayo military base.
Human rights groups say that of the 4,000 dissidents taken to the base, about 50 emerged alive. The army-run base also had a clandestine maternity centre where detained dissidents gave birth and officials took their babies to be adopted by military families.
Bignone was de facto president from 1982 to 1983, but the crimes he was convicted of were committed between 1976 and 1978, when he was a commander at the Campo Mayo base.