The largest of the chameleons from the African mainland, adult
Trioceros melleri generally are in total length (tail included) and in weight, but exceptionally large individuals have reputedly been up to in length and in weight. Females are generally smaller than males, and have less developed dorsal and medial crests. The head of this species is relatively small in relation to the rest of its body and has a more elongated shape in comparison to other chameleons in its
genus.
T. melleri is stout-bodied and has a relatively stubby tail one third the length of its body. A low, scalloped crest extends from just behind the casque of the head through the proximal half of the tail, and a sharp medial crest runs from the lizard's eyes to the tip of its snout, which bears a single small horn. This chameleon bears greatly enlarged
occipital lobes. It has heterogeneous scales which vary shape and size to various parts of its body and large, granular scales distributed homogeneously on the trunk and limbs. There are longitudinal rows of large, granular scales in the chameleon's gular region, one of its most distinctive characteristics. Spots and broad vertical bands on the chameleon's flanks range in color from brown, dark green, yellow or even black. The basic coloration of the creature is a deep
forest green with white stripes, but like many chameleons it can change its color depending on various circumstances. If being fed or handled they might display black and white dots. When basking in the sun, the side of their body towards the sunlight can turn dark green or black, while the rest of the animal stays much lighter. Meller's chameleon has color patterns associated with stress. Mild excitement or stress is indicated by dark spotting overlaying the reptile's normal color. These dark green spots turn to black mottling as the chameleon gets more upset. Severe stress turns the chameleon first charcoal gray, followed by pure white adorned with yellow stripes. A sick Meller's chameleon may be mottled with brown, gray, pink, or white. A
gravid animal is black, cream, and gray colored and will be bulging with eggs. The long tongue can reach prey up to away. ==Diet and reproduction==