In most cases the interaction of a mol. with a metallic surface is well represented by an adiabatic ground-state interaction potential. Nonetheless, recent work has demonstrated the viability of non-adiabatic electronic pathways in some processes, such as surface photochem. and exoelectron emission upon adsorption. The evidence for both types of processes is discussed referring to two recently studied systems-photodissocn. of adsorbed N2O4, and exoelectron emission during the oxidn. of a cesium surface.