A chemisorbed species of CO2 has been observed on Pd(110) in the presence of coadsorbed water. It has been identified using vibrational spectroscopy as a bent, negatively charged CO2-delta species which has previously been observed on a number of clean and alkali metal predosed surfaces. The donation of negative charge from water to the palladium surface is identified as the key factor in the formation of CO2-delta. The catalytic implications of this observation are discussed.