Nine alkali-soluble phenolic acids (gallic acid, protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, caffeic acid, syringic acid, trans-p-coumaric acid, trans-ferulic acid, sinapic acid) in maize stover, and rice and wheat straws were determined by HPLC after alkaline hydrolysis. The most abundant amount of total alkali-soluble phenolic acids was detected in maize stover, followed by rice straw and wheat straw, accounting for, %: 1.23, 1.21 and 0.87 on DM basis, respectively. Trans-p-coumaric acid and trans-ferulic acid were the preponderant phenolic acids in all three kinds of crop residues studied. Nine phenolic acids were found to be present in CAU 108 maize stover, but protocatechuic acid, p-hydroxybenzoic acid and caffeic acid were not detected in rice and wheat straws.