Porous LiNb3O8 nanofibers have been successfully prepared through a simple electrospinning route followed by a post-treatment process. The obtained porous LiNb3O8 nanofibers are composed of polycrystalline LiNb3O8 nanoparticles and numerous nanosized pores. The resulting LiNb3O8 nanofibers exhibit improved capacity and cyclability in virtue of the high surface area, small nanocrystals, and porous structure. In situ XRD studies were carried out to elucidate the Li-storage mechanism for the LiNb3O8 electrodes.