o-Cymene is an organic compound classified as an aromatic hydrocarbon.

It is a flammable colorless liquid which is nearly insoluble in water but soluble in organic solvents.

In addition to o-cymene, there are two other geometric isomers called m-cymene, in which the alkyl groups are meta-substituted, and p-cymene, in which they are para-substituted.

p-Cymene is the only isomer found in nature.

Cymenes can be produced by alkylation of toluene with propylene.