In this study, the physical solubility and diffusivity of N2O in aqueous MDEA + [bmim][BF4] solutions were measured over a range of temperatures of 303-333 K and Ibmim][BNI concentrations of 0-2.0 mol L-1 at atmospheric pressure. The total MDEA concentration in the solutions was kept constant at 4 molL(-1). The "N2O analogy" was then used to estimate the physical solubility and diffusivity of CO2 in aqueous MDEA + Ibmim][BF4] solutions. The density and viscosity of aqueous MDEA + [bmim][BF4] solutions were also measured over the same range of temperatures and concentrations of the ionic liquid. These data were used to develop correlations for the prediction of CO2 diffusivity in these systems. (C) 2011 Published by Elsevier B.V.