The mechanisms leading to anion electron stimulated desorption (ESD) at low energies (0–20 eV) are discussed with emphasis on the formation of transitory anions at surfaces decaying by dissociative attachment (DA). The results of recent measurements are summarized and briefly explained using as examples data on O−ESD from O2condensed on Pt and H−, CH−, and CH−2desorption from hydrocarbons also physisorbed on Pt. It is shown that, when O2and hydrocarbons are coadsorbed on Pt, O−ions formed by DA can undergo reactive scattering with other surface molecules; this reaction leads to the product OH−some of which desorb from the surface.