Most rhinoceros are solitary inhabitants of open grasslands, savannah, scrub forest, or marsh of the African plains, but the Sumatran rhino is now found only in deep forest.

The male mounts the female several times without erection. Copulation lasts approximately 30 minutes. The female conceives at 2 to 4 year time frames. Rhinos carry a long gestation period of between 15 to 16 months.

The square-lipped rhino lives in groups of up to 10 animals though interactions between individuals are usually avoided. Rhinoceros have poor eyesight but acute senses of hearing and smell. Most prefer to avoid men, but males, particularly bad-tempered during the breeding season, and females with calves may charge with a little provocation. The African Black Rhino (Diceros bicornis) is normally ill-tempered and unpredictable and may charge at any unfamiliar sound or smell. Rhinoceros are remarkably agile; the black rhino may attain a speed of about 45 kilometres (30 miles) per hour, even in thick brush and can wheel rapidly after missing a charge.

The rhino pants as a calling sign. They squeal or squeak as sign of danger. They have been known to whine as well.

Modern Rhinoceros are characterised by the possession of one (in the two species of the genus Rhinoceros) or two (in the other three genera) horns on the upper surface of the snout, composed of not the true horn but of keratin, a fibrous protein found in hair.

            Modern rhinoceros are large animals, ranging from 2.5 metres (8 feet) long and 1.5 metres high at the shoulders, in the Sumatran Rhinoceros (Didermocerus, or Dicerorhinus, Sumatrensis), to about 4.3 metres long and 2 metres high in the great Indian Rhinoceros (R. unicornis). Adults of larger species weigh three to five tons. Rhinoceros are noted for their thick skin, which forms platelike folds, especially at the shoulders and thighs.

All rhinos are gray or brown in colour, including the white, or square-lipped (Ceratotherium simum), which tends to be paler than the others. They are nearly or completely hairless, except for the tail tip and ear fringes, but some fossil species were covered with dense fur. The feet of the modern species have three short toes, tipped with broad, blunt nails.