Hydroxycinnamic acids (hydroxycinnamates) are a class of aromatic acids or phenylpropanoids having a C₆–C₃ skeleton. These compounds are hydroxy derivatives of cinnamic acid.

In the category of phytochemicals that can be found in food, there are :

• α-Cyano-4-hydroxycinnamic acid
• Caffeic acid – burdock, hawthorn, artichoke, pear, basil, thyme, oregano, apple
• Cichoric acid
• Cinnamic acid – aloe
• Chlorogenic acid – echinacea, strawberries, pineapple, coffee, sunflower, blueberries
• Diferulic acids
• Coumaric acid
• Ferulic acid (3-methoxy-4-hydroxycinnamic acid) – oats, rice, artichoke, orange, pineapple, apple, peanut
• Sinapinic acid (3,5-dimethoxy-4-hydroxycinnamic acid or sinapic acid)

Hydroxycinnamoyltartaric acids

• Caftaric acid – grapes and wine,^[1] mainly the trans isomer^[2]
• Coutaric acid – grapes and wine, both trans and cis isomers^[2]
• Fertaric acid – grapes and wine, mainly the trans isomer^[2]