Activity coefficients for hydrocarbon solutes at infinite dilution in monoethanolamine have been measured using the medium pressure gas-liquid chromatography method. The hydrocarbon solutes used were n-pentane, n-hexane, n-heptane, n-octane, n-nonane, 1-hexene, 1-heptene, 1-octene, 1-hexyne, 1-heptyne, 1-octyne, cyclopentane, cyclohexane, cycloheptane, cyclooctane, benzene, toluene, o-xylene, m-xylene and p-xylene. Activity coefficients at infinite dilution were determined at the following three temperatures: T = (288.15, 298.15, and 308.15) K. Separation factors are presented for (hexane + monoethanolamine) and (benzene + monoethanolamine) in the solvent monoethanolamine and the results are compared with other solvents. Results indicate that monoethanolamine could be an excellent solvent for the separation of alkane and aromatic mixtures.