The present invention concerns a process for the separation of a gas mixture containing CO.sub.2 and at least one inert gaseous species, comprising (a) feeding the gas mixture into an adsorption column via a first inlet located at a first side of the column, wherein the adsorption column contains a solid CO.sub.2 sorbent loaded with H.sub.2O molecules and thereby desorbing H.sub.2O molecules and adsorbing CO.sub.2 molecules, to obtain a sorbent loaded with CO.sub.2 and an inert product stream; and then (b) feeding a stripping gas comprising H.sub.2O into the adsorption column via a second inlet located at a second side which is opposite to the first inlet, thereby stripping the sorbent and desorbing CO.sub.2 molecules and adsorbing H.sub.2O molecules, to obtain a sorbent loaded with H.sub.2O and the CO.sub.2 product stream, wherein the adsorption column is re-used in step (a) after being stripped in step (b). The invention also concerns an apparatus for performing the process according to the invention.