Abstract: The present invention provides a process for the recovery of base metal sulfides including chalcocite, chalcopyrite, pentlandite and platinum group metal bearing mineral ores. The process involves passing a slurry of the ore through a reagent conditioning stage wherein suitable activators, collectors, frothers and/or depressants are added, further conditioning the slurry with a non-oxidizing gas in a quantity conducive to the separation of the sulfide minerals from the remainder of the ore and subsequently subjecting the slurry to a final flotation treatment with a flotation gas having a higher oxygen content than the non-oxidizing gas. The non-oxidizing gas conditioning can be carried out prior to or after the reagent conditioning stage.