Research on mass transfer of carbon capture process plays an important role in the design of absorbing device. The effects of ammonia concentration, L/G, gas flow rate, gas temperature, CO2 partial pressure and other factors on the volumetric overall mass transfer coefficient (K(G)a(v)), the gas phase mass transfer coefficient (k(G)) and the effective mass transfer cross-sectional area (a(v)) were investigated with ammonia solution as the absorbent in homemade spray tower. Experimental results show that K(G)a(v) has upward trend with the increasing ammonia concentration, L/G and gas flow rate, and first increases and then decreases with the rises of CO2 partial pressure and gas temperature; k(G) increases with the increasing L/G, gas flow rate and CO2 partial pressure; a(v) increases with the increasing ammonia solution and gas flow rates; CO2 partial pressure has less impact on K(G)a(v), k(G) and a(v). Under the experimental conditions, maximums of K(G)a(v), k(G) and a(v) are 0.17 kmol m-3 h(-1) kPa(-1); 0.0022 kmol kPa m(-2) h(-1) and 99.25 m(2) m(-3) respectively. (C) 2013 Elsevier Ltd. All rights reserved.