It is confined to northern Cambodia, with a few birds surviving in extreme southern Laos and a recent sighting in Yok Đôn National Park, Vietnam.

Adults are 102–106 cm (40–41.5 in) long and weigh about 4.2 kg (9.3 lb). Among standard measurements, the wing chord is 52.3–57 cm (20.6–22.4 in), the tail is 30 cm (12 in), the tarsus is 11 cm (4.3 in) and the culmen is 20.8–23.4 cm (8.2–9.2 in). The adults have overall dark grayish-brown plumage with a naked, greyish head and upper neck. There are dark bands across the back of the head and shoulder area and the pale silvery-grey wing tips also have black crossbars. The beak is yellowish-brown, the legs are orange, and the eyes are dark red. Juveniles have short black feathers on the back of the head down to the neck, shorter bills and brown eyes.

It has a loud, ringing call, frequently repeated around dawn or dusk, a-leurk a-leurk.

This species is found in the lowlands, living in swamps, marshes, paddy-fields, open wooded plains, humid clearings, and pools within deciduous dipterocarp lowland forest. It is also found along wide rivers. They have a varied diet consisting of invertebrates, crustaceans, small amphibians and reptiles, and seeds. 

The giant ibis is considered to be Critically Endangered on the IUCN Red List. The current population is estimated at 100 pairs, with a total population (including young and juveniles) of fewer than 500 individuals. In 2018 the IUCN stated there were less than 200 mature individuals in the population.

According to Wikipedia