Adsorption and photooxidation of formamide on TiO2 have been studied by Fourier-transformed infrared spectroscopy. Formamide is adsorbed with intact molecular form (HCONH2(a)) and dissociative form (eta (2)(N,O)-HCONH) on the surface at 35 degreesC. They are subject to decomposition upon UV illumination in O-2. Adsorbed isocyanate (NCO) and formate (HCOO) and gaseous CO2 and N2O are formed-in the photooxidation. CO2 formation mainly results from NCO(a) photodecomposition.