Low energy electron interactions with gas phase monomeric and dimeric forms of glycolaldehyde are reported in the energy range from about 0 to 14 eV, with special emphasis on the formation and decay of transient negative parent ions. Differences between anion fragmentation obtained from monomeric and dimeric forms are observed and discussed. Dissociative electron attachment to the dimeric configuration is shown to have many energetically accessible reaction channels. (C) 2004 Elsevier B.V. All rights reserved.