The present invention relates to a process for treating polyolefin granules in a treatment vessel comprising the steps of: —Providing a bed of granules in liquid in said treatment vessel —Withdrawing a first stream of liquid from said treatment vessel, wherein said first stream of liquid contains hydrocarboneous compounds —introducing a first stream of vapor into said treatment vessel —Withdrawing a second stream of vapor from said treatment vessel wherein said second stream of vapor contains volatile hydrocarboneous compounds —Recovering the granules from said treatment vessel wherein said first stream of vapor has a temperature from Tb to Tb+10° C., wherein Tb is the boiling point of the liquid at the applied pressure, and said first stream of vapor produces an upwards rising vapor stream in said treatment vessel, the superficial vapor velocity of which is no more than 0.2 m/s, and a plant suitable for conducting said process.