The electrolyte equation of state proposed by Furst and Renon (1993, A.I.Ch.E. Journal, 39(2), 335-343) has been applied to the representation of CO2 and H2S solubility in MDEA aqueous solutions over a wide range of temperatures, MDEA concentrations and gas loadings. At low temperatures (298-313 K), it has been shown that the gas solubility could be calculated using, as in the case of strong electrolytes solutions (Furst & Renon, 1993, A.I.Ch.E. Journal, 39(2), 335-343; Zuo & Furst, 1997, Fluid phase Equilibria, 150-151, 567-575), relations between ionic interaction parameters and ionic diameters, assumptions concerning the solvation of the protonated amine allowing to get an estimate of its diameter. The resulting model uses only three adjustable ionic parameters for the representation of CO2 and H2S solubility in MDEA aqueous solutions, the model accuracy being consistent with the experimental deviations. The model was then successfully extended to the representation of a large number of data over the 298-473 K temperature range.