A method for treating polymer particles with steam in a steaming vessel downstream a polymerization process, the method comprising contacting polymer particles with a counter-current flow of steam, wherein the flow rate of steam entering said steaming vessel is continuously maintained proportional to the production rate of said polymer in said polymerization process and to the gradient between the temperature (Tout) of the polymer exiting said steaming vessel and the temperature (Tin) of the polymer entering said steaming vessel.