Abstract: K₃PO₄, K₂HPO₄, and KH₂PO₄ as activating agents were added into the aqueous solution of amino acid salts glycine (GLY) to form activated absorbents (AAb) for CO₂ capture. The performances of GLY and AAb for CO₂ capture were evaluated using a membrane contactorregeneration cycled setup. The effects of activating agent concentration and flow rate on overall voluminal mass transfer coefficient, mass transfer flux, and capture efficiency were studied. The phosphates exhibited remarkable activating effects on CO₂ capture in the membrane contactor; the activation extents of the phosphates were in the order of PO₄^3－＞HPO₄^2－＞H₂PO₄^－. A small amount of activating agent is sufficient to promote the CO₂ capture. The changes of hydrodynamics in the membrane contactor can improve mass transfer performance and enhance mass transfer flux to a certain extent; the essential factor for enhancing the mass transfer efficiency in membrane gas absorption is the performance of absorbents used.