The potential energy surfaces concerning a moderately exoergic reaction, Sc + NO --> ScO + N, and a largely exoergic reaction, SC + O-2 --> SCO + O, were calculated with all-electron multiconfiguration self-consistent-field and configuration interaction methods. There are activation barriers in the initial collision phase of both reactions. The end-on attack appears to be the most efficient for the first reaction, whereas the side-on attack is the most efficient for the second reaction. Two stable forms of the intermediate complex were found for the first reaction, NScO and Sc[NO], in agreement with a recent density functional study. Similarly, two stable isomers are found for the second reaction, OScO (oxo) and SC[021 (peroxo), the former being more stable than the latter. We describe here the general shape of the potential energy surfaces involving these intermediates. The electron transfer from the metal atom occurs at short intermolecular distances in these reactions.