Photodesorption and photodissocn. are induced when O2 adsorbed on Pd (111) is irradiated with UV light. Both processes are nonthermal. Thermal desorption of mol. O is obsd. as a consequence of a displacement process by the nascent at. O. Angle-resolved time-of-flight spectra were recorded. For the adsorbed mol. superoxo species, these measurements show a pronounced translational energy max. at a desorption angle of 60 Deg. Also, this peak is only obsd. at certain azimuthal angles indicating C3v symmetry.