The potential for metallic lithium batteries that exhibit high specific capacities has stimulated a large interest within the energy research field. For safety reasons, the use of metallic lithium anodes requires electrochemically stable electrolytes. However, to date there has been limited success in this area. This work introduces a solid, lithium single-ion conductor thus providing new perspectives in the field of solid-state lithium-batteries. This new-concept material (LiFT), obtained by a direct reaction of nanometric fluorinated titanium oxide (FT) with molten metallic lithium, consists of nanoparticles (NPs) with anionic surface groups that are neutralized with lithium cations. The material displays fast lithium ion transport via an efficient migration mechanism occurring at the interfaces between different nanoparticles. The electrolyte comprises 1.34 mol kg−1 of Li and a conductivity of 2.8·10−4 S cm-1 at 25 °C is demonstrated. This level of performance, in conjunction with a native electrochemical stability towards lithium, extremely low cost starting materials (TiO2) and a facile one-pot synthesis, renders this electrolyte very attractive for applications in future full solid-state lithium batteries.