One of the most important characterization methods for macromolecules is SEC. The main difficulty for this type of measurements concerning metallo-supramolecular polymers based on terpyridines is related to the interaction between the charged supramolecular species and the SEC column material. In this paper, we report new studies on the characterization and the stability of supramolecular polymers based on terpyridine metal complexes utilizing SEC. The main aspects concerning the equilibrium between complexed and uncomplexed species are discussed in detail. The present study reveals a strong relationship between the binding strength of the metal ion used and the stability of the terpyridine metal complex during the SEC measurements, which is in agreement with previously published results regarding the stability of small terpyridine metal complexes in solution. These results can lead to improved analytic possibilities and to a better fundamental understanding of the mentioned metallo-supramolecular polymers. Furthermore, the prepared chain-extended supramolecular-polymer was analyzed by depth-sensing indentation proving an increase in elastic modulus in comparison with the starting material.