Kostermanthus heteropetalus is a tree in the family Chrysobalanaceae. The specific epithet ' is from the Greek meaning 'uneven or unequal petals'.
Kostermanthus heteropetalus grows up to tall with a trunk diameter of up to . The fissured bark is grey-brown. The flowers are pink, tinged white. The fruits measure up to long.
Kostermanthus heteropetalus grows naturally in Sumatra, Peninsular Malaysia, Borneo, the Philippines and Sulawesi. Its habitat is mixed dipterocarp forests from sea-level to elevation.