Pentacene is an polycyclic aromatic hydrocarbon molecule consisting of 5 linearly-fused benzene rings. It has the appearance of a dark-blue powder. It is an organic semiconductor. It is sensitive to light and oxygen. It is a purple powder, but its oxidation product is greenish. Most commercial samples of pentacene are greenish due to oxidized outer layer. Vacuum sublimation or adsorption chromatography are used to purify pentacene.

Researchers from Georgia Institute of Technology are developing new approach for using pentacene combined with buckminsterfullerene in solar panels. Pentacene is also a subject of research for use in organic thin film transistors and OFETs.

Pentacene is one of a series of linear acenes, the previous one being tetracene ( four fused benzene rings) and the next one being hexacene (six fused benzene rings).