Abstract: A process for the purification of an inert gas recycled from a polymerization reactor is disclosed, comprising the steps of mixing the gas with oxygen or gas containing oxygen in stoichiometric quantity or in such an excess that the gas at the outlet of the catalyst bed contains no more than 250 ppm of oxygen, circulating the gas through a catalyst bed comprising platinum, which has been subjected to a reducing environment, at temperatures of no more than 300° C. (572° F.) and preferably no more than 250° C. (482° F.) and recycling the gas to the polymerization reactor.