Monferno is a bipedal, primate-like Pokémon. Orange fur covers most of its body, except for its ears, muzzle, fingers, circular areas on its palms, feet, and chest, which are tan. A small tuft of fur extends from the top of Monferno's head, and it has oval, brown eyes. Its eyes have a thick blue marking above and a small, red marking in-between. Its muzzle is short and blunt, with two small, pointed teeth it its upper jaw. There is a white ruff of fur around its neck and gold bands around its arms near its shoulders. It has five fingers on each hand, but only three toes on each foot. Its long tail has a red ring around the base and a flame burning at the tip.
The flame on Monferno's tail has several purposes. It can be controlled to keep opponents at an ideal distance or stretched in order to make Monferno appear larger. The size of its flame, in combination with brightness of its facial marking, indicates this Pokémon's position in its pack. The bigger the flame and the brighter the pattern, this higher the Pokémon's position. In addition to using its flaming tail as a weapon, Monferno can also leap from ceilings or walls to perform aerial attacks.