In conclusion, using the Li-H-Ti-O ternary compound as an example, it is demonstrated that the confined-water-containing compound shows 2~3 orders of magnitude enhancement in the Li-ion conductivity than water-free compound. The decomposition of nano-confined water narrows the electrochemical stability window of LHTO-pre, but the LHTO has the same electrochemical stability window as the water-free LTO. The enhanced ionic transport in these compounds is attributed to the reduced Li-ion migration barrier due to the shielding effect as well as the formation of the amorphousglassy phase. The good stability window of LHTO can be attributed to the strong covalent bonds of the nano-confined pseudo-water. The performance of LHTO is further demonstrated in a solid-state battery (LiFePO4|LHTO|PEO|Li), which shows excellent rate capability (58% rate retention at 2.0 C) and cyclability (200 stable cycles with 2% capacity loss). Such a discovery not only enhances Li + conductivity in Li-H-Ti-O solid electrolytes, but also opens a new avenue to tune the ionic conductivity of various oxides as solid electrolytes, such as Li-H-Zr-O, Li-H-Cl-O compounds. By controlling the amount, type, and location of the confined water in the oxides, new design freedom in tuning the properties of oxides, including but not limited to ion transport, is introduced, which opens a new avenue in designing novel ceramic materials for various applications.