Volcanion is a primarily maroon, quadruped Pokémon. It has pointed ears with blue interiors, bright blue eyes, yellow markings over and behind its eyes that resemble eyebrows and eyelashes, a pointed, yellow mandible, and a spike-like protrusion on each cheek. Its body is divided into three segments: a considerably larger front portion that has a hunched back, a thin, blue waist, and smaller hips that resemble its front portion. On its chest are four yellow, diamond-shaped bumps. There is a thin, yellow band around each of its leg joints and the lower, maroon portions of its legs are larger than the thin, blue upper portions. Each ankle has a short, blunt growth, while each foot has three yellow claws. Volcanion has a short, tapering tail with a slightly shorter blue bump along the top. On the back of the front portion of its body are two arm-like cannons. These cannons are normally held together and form a ring around the back. Each cannon is separated into three segments by bright blue lines and each segment has a single blue dot and a short, blunt growth. The topmost segments also have four small, yellow bumps around the ends.
The arms on Volcanion's back expel steam from inside its body. It can expel steam of superbly high pressure and has the ability to blow away mountains. As shown in the anime, Volcanion will eventually run out of water. When it does, a sound similar to a bell is heard, the lines and dots on its cannons turn red, and it is unable to use any Water-type moves until it refills its water supply from another source. It was also shown that Volcanion can live for several centuries. Steam Eruption is Volcanion's signature move.
Volcanion appears to be based on the Ryukyuanshisa, or komainu, mythical creatures inspired by lions, tigers, and dogs. Statues of them in pairs are used as guardians that invite good spirits and repel evil ones. Its mechanical appearance and cannon-like "arms" may also draw inspiration from tanks. Its type combination and signature move may refer to geysers. Its ability to fly using its cannon-like "arms" may also draw inspiration from a steam engine.
Volcanion may be a combination of volcano and lion. It may also include canyon, referring to its ability to break large landmasses. "Canion" may also be a corruption of cannon.