The surface composition and structure of a stage-one lithium intercalation compound (Li-GIC) was studied by X-ray photoelectron diffraction (XPD) from Li1s and C1s core levels. The Li-GIC was prepared in situ by vapor phase intercalation of lithium into highly oriented pyrolitic graphite (HOPG) in an ultra-high vacuum system. Stage-one Li-GIC, LiC 6 , having a characteristic golden color, was obtained using Li evaporation onto a HOPG substrate at 400 K, while a metallic lithium overlayer was observed at depositions below room temperature. XPD patterns of Li1s and C1s intensities as a function of the polar emission angle were obtained at a fixed photon energy of 1253.6 eV. The experimental XPD patterns on the HOPG and the stage-one Li-GIC were both in quite good agreement with calculated XPD patterns based on Rehr-Albers separable representation for scattering of the emitted photoelectrons. The structural model for the surface of the Li-GIC producing the best fit to the experimental data has the bulk LiC 6 lattice with surface termination in the graphene plane.