The solubility and diffusion coefficient were determined for carbon dioxide and hydrogen sulfide gases in the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO4]) at temperatures ranging from (303 15 to 353 15) K and pressures up to 1.6 MPa. The Krichevsky-Kasarnovsky equation was used to correlate solubility data and Henry's law constants at different temperatures were obtained The partial molar thermodynamic functions of solution such as Gibbs free energy, enthalpy, and entropy were calculated using the solubility data. A semi-infinite volume approach is used to obtain the diffusion coefficients for CO2 and H2S and a correlation equation with temperature is presented for each gas Comparison showed that H2S is more soluble than CO2 and its diffusion coefficient is about two orders of magnitude as that of CO2 in the ionic liquid studied in this work (C) 2010 Elsevier Ltd All rights reserved