The absorption of carbon dioxide in the 4 mol/L aqueous solution of methyldiethanolamine (MDEA) mixed with three types of ionic liquids, 1-butyl-3-methyl-imidazolium tetrafluoroborate ([bmim][BF4]), 1-butyl-3-methyl-imidazolium acetate ([bmim][Ac]) and 1-butyl-3-methyl-imidazolium dicyanamide ([bmim][DCA]) were measured as a function of temperature, CO2 partial pressure and concentration of ionic liquids in the solution. The data for aqueous MDEA + ILs solutions were obtained for temperature, CO2 partial pressure and ionic liquids concentrations ranging from 303 to 333 K, 100 to 700 kPa and 0 to 2 mol/L, respectively. The CO2 loading in all the studied mixtures decreases with an increase in temperature and increases with an increase in the CO2 partial pressure, at a given temperature. Also, it is found that the CO2 loading decreases significantly as the ionic liquid concentration increases, but this reduction in solutions contained [bmim][BF4] was less than other types of ionic liquids. (C) 2011 Elsevier B.V. All rights reserved.