Both men admitted guilt for the crime committed in 2012.
In Gabon and other parts of West Africa, organs are used as fetishes in magic rituals, "and often are taken from people while they are still alive."
A court in Gabon has jailed two men accused of sacrificing a man and cutting out his organs for black magic rituals, press reports and campaigners said.
Henry Bengone B'Evouna received a life sentence for gunning down Achille Obiang Ndong, while his accomplice, Gerard Mba Eyime, was jailed for 12 years for slicing off the victim's tongue, fingers and toes, l'Union newspaper said.
The sentences were passed on Tuesday by an appeals court in Oyem in the north of the west African country.
Bengone B'Evouna had struck a deal "with a former local dignitary to provide human organs in exchange for the sum of 800,000 CFA francs," about $1,400 or 1,200 euros, l'Union reported.
Both men admitted guilt for the crime committed in 2012, it said.