A fluoride-based cathode (FeF3 center dot 0.33H(2)O) for lithium batteries, the synthesis of which has been reported recently (C. L. Li et al. Adv. Mater. 2010, 22, 3650), is described in terms of structure, morphology, and performance. A self-assembled mesoporous morphology connected with a high specific surface area is obtained through the soft template role of the ionic liquid. The fluoride exhibits a one-dimensional tunnel structure produced by continuous hexagonal cavities, in which hydration water molecules are located. The high Li-intercalation activity of carbon-free FeF3 center dot 0.33H(2)O is expected to be associated with various factors, including electrolyte-infiltratable mesoporosity, wide Li+-insertable channels, and medium conductivities. A single solid-solution reaction mechanism is indicated by potentiostatic intermittent titration technique and ex situ X-ray diffraction at different reactive potentials.