Graphical abstract The HOCO + N reaction makes a chemically activated HOC( O)N intermediate, which dissociates in ∼50 ps by two competing pathways. Research highlights ► The N + HOCO reaction produces a chemically activated HOC( O)N intermediate that dissociates via two competing pathways. ► The ultimate product of the N + HOCO reaction is mostly OH + NCO rather than the energetically favored 3NH + CO 2. ► While the barrier leading from the HOC( O)N intermediate to 3NH + CO 2 is lower than that leading to OH + NCO, the chemically activated HOC( O)N intermediate reacts more rapidly to form OH + NCO. ► The chemically activated HC( O)OH (formic acid) intermediate formed from H + HOCO forms mostly CO + H 2O, not CO 2 + H 2.