戊硼烷是含有5个硼原子的硼烷的总称，有戊硼烷(9)和戊硼烷(11)两种。

戊硼烷(9)的分子式是B₅H₉，为无色挥发性液体，分子具有高度的对称性。

Pentaborane, also called pentaborane(9) to distinguish it from pentaborane(11) (B₅H₁₁), is an inorganic compound with the formula B₅H₉. It is one of the most common boron hydride clusters, although it is a highly reactive compound. Because of its high reactivity toward oxygen, it was once evaluated as rocket or jet fuel. Like many of the smaller boron hydrides, pentaborane is colourless, diamagnetic, and volatile.