The surface-enhanced infrared spectrometry of nitrophenols on copper and silver films has been investigated. When molecules with strong electron-withdrawing groups, such as nitro groups, are adsorbed to coinage-group metals, sizeable changes in the infrared spectrum are observed. These changes can be attributed to donor-acceptor interactions between the nitro group and the metal which change the structure of the molecule. These chemical changes cause spectroscopic changes which influence the suitability of surface-enhanced infrared absorption for use in hyphenated techniques.