Density functional theory (DFT) calculations at the Becke three parameter hybrid functional with the Lee-Yang-Parr nonlocal correlation functional (B3LYP)/6-311+G(d,p) level are performed to study the stability and structures of lithium-excess lithium hydroxide clusters Li-n(OH)(n-1) (n=2-5). These small clusters are stable toward the dissociation to liberate one lithium atom and each of the clusters has structural isomers differing in the stability. The result of calculations implies that the most stable isomer of the clusters with n=2 and 3 have a "hyperlithiated" electronic structure, in which the excess electron fully delocalizes over all of the lithium atoms in the cluster, while the most stable isomer of the clusters with n=4 and 5 in which the excess electron localizes on a specific site has a "segregated" electronic structure composed of the metallic and ionic parts. Vertical ionization energies of the isomers of these clusters calculated by ab initio MO theory at the coupled cluster singles and doubles calculation including a perturbational estimate of the triples excitations [CCSD(T)] and second-order perturbation theory Moller-Plesset (MP2)/6-311+G(d,p) levels depend on the structure; e.g., around 5 eV for the planar isomers, approximately 4.2 eV for the "Li-tail" isomers with one terminal lithium atom, and 3.5 eV or less for the other isomers. The structure dependence of ionization energies reflects a feature of the singly occupied molecular orbital (SOMO) which accommodates the excess electron.