The structure and hydrogen adsorption properties of linear HC C-TMH (TM = Sc-Ni) complexes were systematically investigated using a density functional method. The ground states of the HC C-TMH (TM = Sc-Ni) complexes are 2, 3, 4, 3, 4, 3, 2, and 3. The gravimetric H-2 uptake capacities of these ground state HC C-TMH (TM = Sc-Ni) complexes are 4.54-14.56%. Ab initio molecular dynamic simulations indicated that maximal reversible hydrogen storage densities at 77-300 K of the ground state HC C-TMH (TM = Ti-Co) complexes are 6.65-12.00 wt%. The corresponding average adsorption energies are 0.07-0.49 eV. Due to reasonable superior storage capacity and ideal binding energy, HC C-TMH (TM = Ti-Co) complexes are proposed as a suitable hydrogen storage medium at ambient conditions. When HC C-TMH (TM = Ti, V, Cr) are nonground state structures, they can adsorb one more H-2 molecule than their ground states. Unfortunately, the first adsorbed H-2 molecules are dissociated and the adsorption energies are too large. Therefore, the importance of the multiplicity of sorbents for hydrogen storage is emphasized in this work. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.