Abstract: An experimental apparatus for the measurement of gas-solubility in 1, 2,4-trimethylbenzene was established. The solubility data of pure hydrogen Chloride and chloromethane in the ranges of 293.15-323.15 K and 6-130 kPa and those of the mixture at 298.15 K were obtained and correlated with modified Henrys equation.The activity coefficients were calculated with Margules equation. The solubilities of hydrogen, nitrogen, carbon monoxide, argon, methane, hydrogen chloride and chloromethane at 298.15 K and 101.3 kPa were also observed.Results obtained compared well with those from the Scatchard-Hildebrand theory, except the solubility of hydrogen.