Structures, energetics, and reactions of anions derived from cyclooctatetraene [C8H8-(1), C8H7- (2 alpha), and C8H6-(3)] have been studied using the selected ion flow tube (SIFT) technique and molecular orbital (MO) calculations. Radical anions 1 and 3 undergo electron detachment upon collisional excitation with helium whereas anion 2 alpha undergoes a remarkable rearrangement to an isomeric species, C8H7-(2 beta). The anion 2 alpha is not a vinylic species but rather a novel structure incorporating a pi-electronic system and an allenic moiety within the eight-membered ring. The anion 2 beta is a relatively stable [3.3.0] bicyclic species with a proton affinity and electron binding energy very similar to those for cyclopentadienide ion. The molecular structures are predicted and the mechanisms of isomerization are elucidated using MO calculations. Bimolecular reactions of these anions are thoroughly examined with NO, NO2, SO2, COS, CS2, and O-2 The reactivity of 2 alpha is interpreted in terms of the high proton affinity and the strain of the allenic bond. Anion 3 exhibits a remarkable reaction with NO to yield CN-. The adiabatic electron affinity of cyclooctatetraene has been unambiguously determined as 0.55 +/- 0.02 eV from equilibrium measurements with the SIFT technique : Heats of formation for the anions and their corresponding neutrals, along with the homolytic C-H bond dissociation energies for the conjugate acids, have also been determined.