The invention relates to a process for increasing the molecular weight of a polyamide via solid-state post-condensation by exposing the polyamide in the solid-state at elevated temperature to an inert gas atmosphere, that comprises a step (a) wherein the gas atmosphere to which the polyamide is exposed has a dew temperature Tdew-1, followed by a step (b) wherein the gas atmosphere to which the polyamide is exposed has a dew temperature Tdew-2, whereby Tdew-1 is higher than Tdew-2. The effect is that a high molecular weight polyamide can be obtained in a shorter production time.