Acacia rubricaulis is a shrub belonging to the genus Acacia and the subgenus Juliflorae that is native to a small area in north eastern Australia.
The shrub typically grows to a height of . The stout branchlets have a polished appearance and are a dark red colour and glabrous. The branchlets are usually steeply angled towards the apex. Like most species of Acacia it has phyllodes rather than true leaves. The evergreen phyllodes have an ovate or elliptic shape and are usually straight or slightly sickle shaped. The glabrous phyllodes have a length of and a width of with three longitudinal nerves that are more prominent than the rest.[1] When it blooms it produces simple inflorescences simple in pairs in the axils with cylindrical flower-spikes that are sub-densely flowered and have a length of in length but can reach up to in length. The seed pods that form after flowering are flat and glabrous and have a narrowly oblong shape with a length of and a width of .[1]
It is endemic to the northern part of Cape York Peninsula where it is situated on degraded sand dunes, on dune fields and creek banks growing in sandy soils.[1]