LiSbO2 has been synthesized using a ceramic method involving evacuated quartz tubes to ensure stoichiometry. Its structure [monoclinic, P2(1)/c; a = 4.8550(3) angstrom, b = 17.857(1) angstrom, c = 5.5771(3) angstrom; beta = 90.061(6)degrees] has been determined using X-ray and neutron diffraction and refined on the basis of neutron data. The structure is significantly different from that of LiBiO2 and contains chains of corner-linked SbO3 trigonal pyramids, which provide a framework for the tetrahedral coordination of Li+ ions. A layer structure results in which the Li sites are located in planes perpendicular to [010]. LiSbO2 is stable in air up to ca. 400 degrees C, but at higher temperatures, oxidation to LiSbO3 occurs as a two-stage process, with evidence for a metastable, intermediate LiSbO2.5 phase presented. The Li+-ion conductivity, measured using alternating-current impedance spectroscopy, is similar to that of LiBiO2, with a value of ca. 10(-6) S cm(-1) at 300 degrees C.