Minimum energy pathways for the rearrangement of the anions of the water trimer and tetramer anions between their cyclic and chain structures were investigated by means of ab initio electronic structure calculations, coupled with nudged elastic band optimizations. The rearrangements of both anions are found to proceed by opening of the cyclic structure and reorientation of the water molecules as the excess electron migrates to the terminal water fragment with the dangling hydrogens. The activation energies for the cyclic-->chain rearrangements are calculated to be 0.11 and 0.32 eV for (H2O)(3)(-) and (H2O)(4)(-), respectively.