Abstract: The present invention relates to a method for automatically determining the relative solution viscosity and/or the melt volume flow rate of a polymer, during a phase of the process for producing the polymer, where the polymer is in a solution with 10 to 20% by weight of the polymer in an organic solvent. The method includes continuously removing a substream of the polymer solution from a component of the process for producing the polymer, wherein the polymer solution is essentially free from inorganic salts; removing a sample having a volume of from 1 to 10 ?l from the substream; introducing the sample into a gel permeation chromatography apparatus and determining the gel permeation chromatography data for the polymer; and automatically determining the relative solution viscosity and/or the melt volume flow rate of the polymer from the data obtained from the gel permeation chromatogram, on the basis of calibration relationships.