Primarily nocturnal, Gaboon Vipers have a reputation for being slow-moving and placid. They usually hunt by ambush, often spending long periods motionless, waiting for suitable prey to pass by. On the other hand, they have been known to hunt actively, mostly during the first six hours of the night. They are usually very tolerant snakes, even when handled, and rarely bite or hiss, unlike most vipers. However, bites by bad-tempered individuals do occur.
If threatened, they may hiss loudly as a warning, doing so in a deep and steady rhythm, slightly flattening the head at the expiration of each breath. Despite this, they are unlikely to strike unless severely provoked; however, they are one of the fastest-striking snakes in the world, so care should be taken in handling them.
Because of their large, heavy body size, the adults have no trouble eating prey as large as fully grown rabbits. When prey happens by, they strike with very fast precision from any angle. Once they strike their prey, they hang on to it with their large fangs rather than letting it go and waiting for it to die. This behavior is very different from the behavior of other species of vipers. These snakes feed on a variety of birds and mammals, such as doves, many different species of rodents, including field mice and rats, as well as hares and rabbits.