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.
It is a crystalline solid that is slightly soluble in water, but well soluble in ethanol and diethyl ether.
Together with sinapyl alcohol and coniferyl alcohols, p-coumaric acid is a major component of lignin