Phenolic acids or phenolcarboxylic acids are phenolic compounds and types of aromatic acid compounds. Included in that class are substances containing a phenolic ring and an organic carboxylic acid function (C6-C1 skeleton). Two important naturally occurring types of phenolic acids are hydroxybenzoic acids and hydroxycinnamic acids, which are derived from non-phenolic molecules of benzoic and cinnamic acid, respectively.^[1]

Phenolic acids can be found in many plant species. Their content in dried fruits can be high.

Natural phenols in horse grams (Macrotyloma uniflorum) are mostly phenolic acids, namely 3,4-dihydroxy benzoic, p-hydroxy benzoic, vanillic, caffeic, p-coumaric, ferulic, syringic, and sinapinic acids.^{[citation needed]}

Phenolic acids can be found in several mushroom-forming species of basidiomycetes.^[2] It is also a part of the humic substances, which are the major organic constituents of soil humus.

Many phenolic acids can be found in human urine.^[3]

Immobilized Candida antarctica lipase can be used to catalyze the direct acetylation of flavonoids with phenolic acids.^[4]

• Benzoic acid
• Aromatic alcohol
• List of phytochemicals in food