The densities and viscosities of aqueous N-methyldiethanolamine/monoethanolamine (MDEA/MEA) blends containing 30 and 40 mass % total amine with MEA concentrations of 5, 10, and 15 mass % of the total amine concentration were measured at temperatures of 303, 313, and 323 K. The diffusion coefficients and Henry’s law constants of N2O in these solutions were also measured and were used to estimate the diffusion coefficients and Henry’s law constants of CO2 in these solutions according to the "N2O/CO2 analogy" technique.