Ti-doping and Li-vacancy (V-Li) crucially affect the dehydrogenation properties of LiBH4 surface. However, theoretical investigations on individual Ti or V-Li could not completely explain experimental observations. In this article, we investigated the synergistic effects of co-existing Ti and V-Li on the dehydrogenation properties of LiBH4 (010) surface. Our result shows mutual stabilization between Ti-dopant and Li-vacancy, implying expectable coexistence of Ti and V-Li. Thermodynamic destabilization from composite Ti + V-Li defect agrees with experiments better than that from single Ti or V-Li. The kinetic barrier on Ti + V-Li decorated surface also becomes closer to experimental result. Therefore, the coexisting Ti and V-Li synergistically and crucially affect the dehydrogenation thermodynamics and kinetics on LiBH4 surface. The electronic structure further reveals strong H-H, B-B, and Ti-B bonds as well as weakened B-H bond in transition states on Ti + V-Li co-existed surface, which is the main factor of low kinetic barrier. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.