Since the triple-helical collagen model peptides with a free N-terminus have three cationic groups at one end, it may have strong interactions with polyelectrolytes. In this study, complex formation behavior was investigated for sodium carboxymethyl amylose (NaCMA) + H-(Pro-Pro-Gly)(10)-OH (PPG10), a collagen model peptide, in aqueous NaCl with ionic strength of 10 mM and 100 mM by means of small-angle X-ray scattering (SAXS) and circular dichroism at different temperatures. The previously reported [Macromolecules 2012, 45, 392-400] sodium polyacrylate (NaPAA) and H-(Gly-Pro-4-(R)-Hyp)(9)-OH (GPO9) system was also investigated to elucidate complex formation nearby the transition temperature region between triple helix and single coil of the peptide. The complex formed near the melting temperature of the triple helices, confirmed that the triple helical structure is directly related to the complex formation. (C) 2015 Elsevier Ltd. All rights reserved.