The limbs are like the back in color, and the hands, feet, and tail are scantily covered with fine white hairs. Fine scales are conspicuous on the tail. The body is streamlined, the head is long and like that of Hydromys, the ears are short and round, the eyes are small, the tail is much shorter than the head and body, and the coat is water-resistant. Nonetheless, the feet are not webbed, and there is some question whether Xeromys is aquatic. There are only two molar teeth on each side of the skull.
Females have four mammae.
It is an agile climber and is well adapted to tidal areas. It builds its nest among the roots of mangrove trees. The nest is a mound of leaves and mud about 60 cm high with a single opening near the apex. A narrow tunnel from the opening leads to a nest chamber, from which radiate numerous interconnecting tunnels, some going well below ground level. It was seen only in small trees lining the rivers, climbing agilely among the branches.