The capability of La2LiHO3 as a H- conductive solid electrolyte has recently been demonstrated, which has suggested the possibility of developing electrochemical devices based on H- conduction. However, the performance of La2LiHO3 as a solid electrolyte has not yet been fully clarified. In this study, we prepared La2LiHO3 sintered pellets by a conventional solid-state reaction with LiH flux under ambient pressure and characterized the crystal structure and thermal stability (to moisture, ambient air, and oxygen) by neutron and X-ray diffraction measurements. The produced sintered pellets exhibited an activation energy of 69.2kJ/mol, which is consistent with the value of the sample synthesized by the high-pressure method. The gas-sealing properties of the sintered La2LiHO3 pellets as the H- conductive solid electrolyte were confirmed by measuring the electromotive force using a hydrogen concentration cell.