Ferulic (FA) and p-coumaric (pCA) acids are phenolic compounds of considerable interest in plant science, human health and other industries. In the grain, FA and pCA are mainly bound to several cell wall polymers: arabinoxylan, lignin, cutin and suberin. They derive from the phenylpropanoid pathway which also produces lignin monomers and flavonoids. They are transferred to cell wall polymers by the action of acyl transferases of the BAHD family. In oxidative conditions they form radicals and can promote linkages between cell wall polymers. Their amount is variable between cereal species, between genotypes of a same species, in different tissues of the grain, during grain development and in response to pathogen attack. Biological functions were ascribed to bound FA in cell wall assembly, in tissue stiffening, in resistance to pathogens. Bound to cereal grain polymers FA has technological impacts in milling, bread-making and gelling. Free FA extracted from plant tissues has applications in bioconversion and has been associated to many health benefits.