A composition for removing mercaptan from a gas stream containing at least one acid gas in addition to a mercaptan, the composition comprising a physical and/or chemical solvent for H2S and an inclusion compound for the mercaptan. A process of treating gas stream using the composition. The inclusion compound is selected from the group consisting of, cyclodextrin, cryptand, calixarene, cucurbituril. The chemical solvent may be monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA, diisopropylamine (DIPA), diglycolamine (DGA) and methyldiethanolamine (MDEA). Examples of useful physical solvents include cyclotetramethylene sulfone (sulfolane) and its derivatives, aliphatic acid amides, NMP (n-methylpyrrolidone), N-alkylated pyrrolidones and corresponding piperidone, methanol and mixtures of dialkethers of polyethylene glycols. The method copirses scrubbing preferably the natural gas with an aqueous solution comprising the above compounds followed by a stripping regeneration step.