From ab initio density functional theory (DFT) calculations, the structural stability and hydrogen adsorption capacity of transition metal (TM, TM = Sc, Ti, V, Cr, Mn) decorated covalent triazine-based framework (CTF) are discussed. It is found that by calculation, these TM atoms can adsorb on the CTF sheet without clusters. The Sc, Ti, V, Cr and Mn decorated CTF are predicated to bind five, four, three, three and two of hydrogen molecules. We found that Sc and Ti decorated CTF are suitable candidates for effective reversible hydrogen storage at near ambient condition, whereas V, Cr and Mn decorated CTF are not promising materials due to too large average bind energies per hydrogen molecule. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.