Hydride (H - ) conduction is a new frontier related to hydrogen transport in solids. Here, a new H - conductive oxyhydride Ba 2 ScHO 3 was successfully synthesized using a high-pressure technique. Powder X-ray and neutron diffraction experiments investigated the fact that Ba 2 ScHO 3 adopts a K 2 NiF 4 -type structure with H - ions preferentially occupying the apical sites, as supported by theoretical calculations. Electrochemical impedance spectra showed that Ba 2 ScHO 3 exhibited H - conduction and a conductivity of 5.2 × 10 -6 S cm -1 at 300 °C. This value is much higher than that of BaScO 2 H, which has an ideal perovskite structure, suggesting the advantage of layered structures for H - conduction. Tuning site selectivity of H - ions in layered oxyhydrides might be a promising strategy for designing fast H - conductors applicable for novel electrochemical devices. © Copyright 2019 American Chemical Society.