We have measured the intensity of O− ions produced by low‐energy electrons (1–20 eV) impinging on NO and N2O molecules condensed on a polycrystalline platinum surface held at 17 and 40 K. In condensed NO (i.e., in the dimerized form N2O2), the energy dependence of the O− yield exhibits four broad peaks within the range 5–20 eV whereas in condensed N2O two peaks are observed at 9.4 and 16.4 eV. The linearity of O− production near the peak energies with coverage indicates the presence of a first‐order mechanism which we ascribe to the decay of transient anion states (i.e., electron resonances) into the dissociative attachment channel.