Castanopsis clemensii is a tree in the family Fagaceae. It is named for the American chaplain and plant collector Joseph Clemens.
Castanopsis clemensii grows as a tree up to 30m (100feet) tall with a trunk diameter of up to 50cm (20inches). The yellowish white bark is smooth or cracked or lenticellate. The coriaceous leaves measure up to 12cm (05inches) long. Its ellipsoid nuts measure up to 21NaN1 long.
Castanopsis clemensii is endemic to Borneo. Its habitat is lower montane forests to 1300m (4,300feet) altitude.