The interaction of low energy (0–10 eV) electrons with gas phase and condensed phase 1,3-chloronitrobenzene (m-ClNB) is studied by means of a mass spectrometric detection of negatively charged (fragment) ions. The gas phase molecule yields a long-lived metastable parent anion at low electron energies, and different fragment ions from resonant features in the energy range 0–5 eV with Cl− and NO2- as the predominant products. Electron stimulated desorption (ESD) of anions from solid state m-ClNB also occurs through resonant features, but only in the energy range above 5 eV yielding the ions O−, OH− and Cl−. These results illustrate the strong influence of the medium on the formation of free anions.