HBGS (Hydrate-based gas separation) is a potential method for CO2 capture from fossil fuel power plants. High hydrate formation rates and low energy consumption are still the demands for industrial application of HBGS. The promotion effects of three additive mixtures (THF (tetrahydrofuran) + TBAB (tetra-n-butyl ammonium bromide)) on flue gas (CO2/N-2) hydrate phase equilibrium and CO2 capture characteristics were experimentally investigated in this study. It was found that hydrate phase equilibrium pressure for the 5% THF + 5% TBAB mixture was almost the same as that for the 5% THF + 10% TBAB mixture. Both the gas consumption and CO2 recovery increased substantially with increases in the mass fractions of THF or/and TBAB. The experimental results also showed that the gas consumption increases with the enhancement of initial pressure. Considering the hydrate phase equilibrium conditions and gas separation efficiency, an additive mixture with a mass fraction of 5% THF + 10% TBAB was found to be a better choice for hydrate-based CO2 capture from flue gas relative to other additive mixtures investigated in this study. (C) 2016 Elsevier Ltd. All rights reserved.