Gel permeation chromatography (GPC) and gas chromatography (GC) were successfully introduced into a high-throughput workflow. The feasibility and limitations of online GPC with a high-speed column was evaluated by measuring polystyrene standards and comparison of the results with regular offline GPC measurements. The reliability of the online GC characterization was investigated by monitoring the cationic ring-opening-polymerization of 2-ethyl-2-oxazoline, whose polymerization kinetics were determined by both online and offline GC.