The article describes the equilibrium conditions for the semiclathrate hydrates formed in the following three ternary systems, CO2 + tetrabutylphosphonium bromide + water system, CH4 + tetrabutylphosphonium bromide + water system, and N-2 + tetrabutylphosphonium bromide + water system. The experiments were performed at temperatures between 282.6 and 291.6 K, at pressures between 0.15 and 5.10 MPa with tetrabutylphosphonium bromide aqueous solution of w(TBPB) = 0.35, where w(TBPB) denotes the mass fraction of tetrabutylphosphonium bromide, respectively. The equilibrium pressure at a given temperature was lower in the order of CO2, CH4 and N-2 thereby indicating the possibility of capturing CO2 from the CH4 + CO2 and N-2 + CO2 mixtures. (C) 2013 Elsevier B.V. All rights reserved.