p-Coumaric acid is a hydroxycinnamic acid, an organic compound that is a hydroxy derivative of cinnamic acid. There are three isomers of coumaric acid—o-Coumaric acid, m-Coumaric acid, and p-Coumaric acid—that differ by the position of the hydroxy substitution of the phenyl group. p-Coumaric acid is the most abundant isomer of the three in nature. p-Coumaric acid exists in two forms trans-p-Coumaric acid and cis-p-Coumaric acid.

p-Coumaric acid can be found in Gnetum cleistostachyum. p-Coumaric acid can be found in a wide variety of edible plants such as peanuts, navy beans, tomatoes, carrots, and garlic. It is found in wine and vinegar. It is also found in barley grain. p-Coumaric acid from pollen is a constituent of honey. p-Coumaric acid glucoside can also be found in commercial breads containing flaxseed. Diesters of p-Coumaric acid can be found in carnauba wax.

p-Coumaric acid has antioxidant properties and is believed to reduce the risk of stomach cancer by reducing the formation of carcinogenic nitrosamines.