Solubilities of O-2, N-2, H-2, and CH4 in 1,1,3,3-tetramethylguanidium lactate (TMGL) at the temperatures ranging from (308 to 327) K and the pressures ranging from (0 to 11) MPa were measured. The solublilities were correlated using the Krichevisky-Kasarnovsky equation, from which Henry's constants and partial molar volumes of these four gases were obtained. It was found that the solubilities increase with increasing pressure and decrease with increasing temperature. The solubilities of these four gases in TMGL follow the sequence x(CH4) > x(O2) > x(N2) > x(H2) (i.e.. H-CH4 < H-O2 < H-N2 < H-H2). Comparing the solubility data of these four gases with that of CO2 in TMGL, it is observed that the solubilities of these four gases in TMGL are much lower than that of CO2. This means that TMGL may be used as a potential solvent for capturing CO2 from mixed gases.