The mechanisms of the reaction of W and W+ with the N2O were investigated at the CCSD(T)/[SDD+6-311G(d)]//B3LYP/[SDD+6-31G(d)] level of theory. It was shown that the reaction of W(S-7) + N2O((1)Sigma(+)) is a multi-state process, involves several lower-lying electronic states of numerous intermediates and transition states, and leads to oxidation, WOd((3)Sigma) + N-2 ((1)Sigma(+)(g)) with a negligible barrier and/or nitration, WN((4)Sigma) + NO((2)Pi) with a barrier of 6.7 kcal/mol relative to reactants. The reaction of W+ with N2O, resemble its neutral analog, proceeds via the insertion and direct abstraction pathway, leads to oxidation and nitration of the W-center. (C) 2009 Elsevier B. V. All rights reserved.