A water stable and water penetration free high lithium ion conducting solid electrolyte sheet of Li1.4Ti1.6Al0.4(PO4)(3) (LTAP) was prepared by hybridization with an epoxy resin. The LTAP fine powder was synthesized using a sol-gel method. A LTAP thin sheet (about 200 mu m) was prepared via a tape casting method using a slurry of the mixture of the fine LTAP powder and a TiO2 fine powder (3 weight%). The tape-cast green sheet was sintered at 1060 degrees C for 2 h. 2,2-bis(4-glycidyloxyphneyl)propane and 1,3-phenylenediamine in tetrahydrofuran was poured into the sintered LTAP sheet and was polymerized by heating at 150 degrees C for 24 h. The obtained LTAP-epoxy hybrid sheet was water-penetration free, and the electrical conductivity was 4x10(-4) Scm(-1) at 25 degrees C. This conductivity value is comparable to that of the sintered pellets reported previously. The lithium metal electrode protected with a lithium conducting polymer electrolyte, and the LTAP-epoxy hybrid electrolyte sheet showed no resistance change for 20 days in a saturated LiOH and LiCl aqueous solution. The water stable lithium metal electrode has a potential application for aqueous lithium air rechargeable batteries. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.072207jes] All rights reserved.