o-Toluic acid, also 2-methylbenzoic acid, is an aromatic carboxylic acid, with formula (CH<sub>3</sub>)C<sub>6</sub>H<sub>4</sub>(COOH). It is an isomer of p-toluic acid and m-toluic acid. When purified and recrystallized, o-toluic acid forms needle-shaped crystals. o-Toluic acid was first noticed by Sir William Ramsay, credited discoverer of the noble gases and winner of the 1904 Nobel Prize in Chemistry.
o-Toluic acid is prepared by oxidation of o-xylene with nitric acid.