We have examained the interaction of discharge effluents to understand the formation mechanism of N2O in the upper atmosphere and in published studies employing discharge-flow systems. N2O production rates were determined under various discharge-flow conditions and are consistent only with a process in which both N2 and O2 species are excited and are present in large relative concentrations. We postulate N2(v≥15)+ O2(a1Δ or b1∑) as the responsible mechanism. ¿ American Geophysical Union 1990