[2] The common potoo was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae.

[3] Gmelin based his description on "L'engoulevent gris" from Cayenne that had been described from a preserved specimen in 1779 by the French polymath Georges-Louis Leclerc, Comte de Buffon.

[8] Two subspecies are recognised:[6] Common potoos are 34–38 cm (13–15 in) long with mottled red-brown, white, black, and grey cryptic plumage.

The upper and lower eyelids can be moved independently and rotated over the eye into the desired position so that the bird may adjust its field of vision.

[17] It avoids cooler montane regions; it is rarely observed over 1,900 m (6,200 ft) above mean sea level even in the hottest parts of its range.

A bit further south, where the amount of wood-versus grassland is somewhat lower, it is decidedly rare, and due west, in the Entre Ríos Province of Argentina with its abundant riparian forest, it is likewise not common.

[21] Most potoos choose stumps and other natural materials on which to rest, but some adults have been spotted perching on human-made items.

[21] The potoo sits with its eyes open and its bill horizontal while awake, but if disturbed, assumes an alert "freezing" posture.

[11] If disturbed by larger animals, such as common marmosets (Callithrix jacchus), it may break its camouflage and try to chase the threat away.

It uses its wide mouth to capture insects such as flies and moths, but also ants, other hymenopterans, termites, grasshoppers, locusts, and crickets.

[25] After mating, the female lays a single white egg with lilac spots directly into the depression in a tree limb.

[23] Young potoos hatch after about 33 days, using their egg tooth to break free and emerge as downy individuals with pale brown and white stripes.