3-Octanone is an organic compound with the formula C5H11C(O)C2H5.

A colorless fragrant liquid, it is classified as a ketone.

3-Octanone is found in a variety of sources such as plants (such as lavender),[3] herbs (such as rosemary,[4] basil, and thyme[5]), and nectarines.

[6] It was also found to be present in Japanese catnip (Schizonepeta tenuifolia)[7] and the pine king bolete (Boletus pinophilus).

[8] It is produced by oyster mushrooms as an insecticide to kill roundworms.