Abstract: A process for the absorption of one or more gas(es) selected from the group consisting of carbon dioxide, hydrogen sulfide, sulfur oxides, nitrogen oxides and carbon monoxide from a fluid, the process including: providing a fluid containing the selected gas(es); and an ionic liquid absorbent, the absorbent including the components: one or more anions; one or more metal species; and optionally one or more organic cations; and optionally one or more ligands; the absorbent components being selected such that the absorbent is in a liquid state at the operating temperature and pressure of the process; with the provisos that: when the anion contains in the same molecular entity: both an amine functional group and a sulfonate functional group; both an amine functional group and a carboxylate functional group; both a phosphine functional group and a sulfonate functional group; or both a phosphine functional group and a carboxylate functional group, the metal species is not an alkali metal or alkaline earth metal; the